Support extension additional settings with extension REST initialization

[cwperks]

Description

This PR modifies the RestInitializeExtensionAction to extract any additional settings supplied from ExtensionAwarePlugin.getExtensionSettings <- utilized by the security plugin to define security settings for extensions.

I tested this change by running an extension locally and defining settings from the Security plugin and calling on the API to initialize an extension. I plan to test different types of settings, booleans, strings, arrays, etc to verify this works with different types of settings. I was not able to modify the test to show this working from a test case, but plan to add an automated test ASAP. This PR uses Mockito to partially mock ExtensionsManager to show how additional settings work with the REST endpoint for extension initialization.

Related Issues

Resolves #8032

Check List

• New functionality includes testing.
  • All tests pass
• New functionality has been documented.
  • New functionality has javadoc added
• Commits are signed per the DCO using --signoff
• Commit changes are listed out in CHANGELOG.md file (See: Changelog)

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[cwperks]

@owaiskazi19 This PR shows the REST Extension initialization working with settings defined from a plugin like the security plugin.

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: UNSTABLE ❕
• TEST FAILURES:

      1 org.opensearch.remotestore.SegmentReplicationUsingRemoteStoreIT.testNodeDropWithOngoingReplication

• URL: https://build.ci.opensearch.org/job/gradle-check/18982/
• CommitID: 3bdf909
  Please review all flaky tests that succeeded after retry and create an issue if one does not already exist to track the flaky failure.

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: UNSTABLE ❕
• TEST FAILURES:

      2 org.opensearch.remotestore.SegmentReplicationUsingRemoteStoreIT.testNodeDropWithOngoingReplication
      1 org.opensearch.remotestore.SegmentReplicationUsingRemoteStoreIT.testDropPrimaryDuringReplication

• URL: https://build.ci.opensearch.org/job/gradle-check/18983/
• CommitID: 3173858
  Please review all flaky tests that succeeded after retry and create an issue if one does not already exist to track the flaky failure.

[codecov]

Codecov Report

Merging #8414 (fdb3689) into main (1d22740) will increase coverage by 0.07%.
The diff coverage is 72.50%.

❗ Current head fdb3689 differs from pull request most recent head 4d436d4. Consider uploading reports for the commit 4d436d4 to get more accurate results

@@             Coverage Diff              @@
##               main    #8414      +/-   ##
============================================
+ Coverage     70.81%   70.89%   +0.07%     
- Complexity    56830    56911      +81     
============================================
  Files          4757     4757              
  Lines        269136   269130       -6     
  Branches      39403    39392      -11     
============================================
+ Hits         190585   190789     +204     
+ Misses        62445    62241     -204     
+ Partials      16106    16100       -6     

Impacted Files	Coverage Δ
...org/opensearch/extensions/ExtensionDependency.java	73.68% <ø> (+7.01%)	⬆️
...extensions/rest/RestInitializeExtensionAction.java	69.73% <71.79%> (-3.28%)	⬇️
...a/org/opensearch/extensions/ExtensionsManager.java	43.87% <100.00%> (+0.36%)	⬆️

... and 484 files with indirect coverage changes

[cwperks]

I was able to successfully setup tests using Mockito to partially mock the extensions manager.

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: UNSTABLE ❕
• TEST FAILURES:

      1 org.opensearch.snapshots.RestoreSnapshotIT.testRestoreInSameRemoteStoreEnabledIndex
      1 org.opensearch.remotestore.SegmentReplicationUsingRemoteStoreIT.testNodeDropWithOngoingReplication

• URL: https://build.ci.opensearch.org/job/gradle-check/18991/
• CommitID: 42c6580
  Please review all flaky tests that succeeded after retry and create an issue if one does not already exist to track the flaky failure.

[owaiskazi19]

Overall LGTM! @dbwiddis need another pair of eyes

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: UNSTABLE ❕
• TEST FAILURES:

      2 org.opensearch.remotestore.SegmentReplicationUsingRemoteStoreIT.testNodeDropWithOngoingReplication
      1 org.opensearch.remotestore.SegmentReplicationUsingRemoteStoreIT.testDropPrimaryDuringReplication

• URL: https://build.ci.opensearch.org/job/gradle-check/18993/
• CommitID: fdb3689
  Please review all flaky tests that succeeded after retry and create an issue if one does not already exist to track the flaky failure.

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: UNSTABLE ❕
• TEST FAILURES:

      1 org.opensearch.remotestore.SegmentReplicationUsingRemoteStoreIT.testNodeDropWithOngoingReplication

• URL: https://build.ci.opensearch.org/job/gradle-check/18998/
• CommitID: d660042
  Please review all flaky tests that succeeded after retry and create an issue if one does not already exist to track the flaky failure.

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: UNSTABLE ❕
• TEST FAILURES:

      1 org.opensearch.remotestore.SegmentReplicationUsingRemoteStoreIT.testNodeDropWithOngoingReplication
      1 org.opensearch.cluster.allocation.AwarenessAllocationIT.testThreeZoneOneReplicaWithForceZoneValueAndLoadAwareness

• URL: https://build.ci.opensearch.org/job/gradle-check/18999/
• CommitID: 8c11fd9
  Please review all flaky tests that succeeded after retry and create an issue if one does not already exist to track the flaky failure.

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: UNSTABLE ❕
• TEST FAILURES:

      1 org.opensearch.remotestore.SegmentReplicationUsingRemoteStoreIT.testNodeDropWithOngoingReplication

• URL: https://build.ci.opensearch.org/job/gradle-check/19001/
• CommitID: 9f2068c
  Please review all flaky tests that succeeded after retry and create an issue if one does not already exist to track the flaky failure.

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: UNSTABLE ❕
• TEST FAILURES:

      1 org.opensearch.remotestore.SegmentReplicationUsingRemoteStoreIT.testNodeDropWithOngoingReplication

• URL: https://build.ci.opensearch.org/job/gradle-check/19002/
• CommitID: 4d436d4
  Please review all flaky tests that succeeded after retry and create an issue if one does not already exist to track the flaky failure.

[opensearch-trigger-bot]

The backport to 2.x failed:

The process '/usr/bin/git' failed with exit code 128

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add ../.worktrees/backport-2.x 2.x
# Navigate to the new working tree
pushd ../.worktrees/backport-2.x
# Create a new branch
git switch --create backport/backport-8414-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 a0299fceda9900f8bfdbf8b0229ad1e8884a4fd4
# Push it to GitHub
git push --set-upstream origin backport/backport-8414-to-2.x
# Go back to the original working tree
popd
# Delete the working tree
git worktree remove ../.worktrees/backport-2.x

Then, create a pull request where the base branch is 2.x and the compare/head branch is backport/backport-8414-to-2.x.

[owaiskazi19]

@cwperks looks like this one needs a manual backport to 2.x.

[cwperks]

@owaiskazi19 Manual backport created: #8445