Register MediaTypes through SPI

[nknize]

This PR provides a new SPI interface MediaContentProvider. Modules, Plugins, Extensions, implement this interface and provide the concrete MediaType implementations (and MIME aliases) through getMediaTypes and getAdditionalMediaTypes, respectively. This enables downstream extensions (e.g., serverless or cloud native implementations) as well as plugins or core modules to register their own custom MediaType through the interface. All types are registered through ServiceLoader.load(MediaTypeProvider.class) when the classloader loads the MediaTypeRegistry instead of having to register the types explicitly in application code. XContentType is also cutover to use this SPI interface through the :libs:opensearch-x-content library and the manual registration logic in TransportService is removed.

relates #5910
relates #8110

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/21182/
• CommitID: f522242
  Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green.
  Is the failure a flaky test unrelated to your change?

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: UNSTABLE ❕
• TEST FAILURES:

      1 org.opensearch.search.suggest.CompletionSuggestSearchIT.testSkipDuplicates

• URL: https://build.ci.opensearch.org/job/gradle-check/21185/
• CommitID: 963bc41
  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 #8938 (d64bef5) into main (5495c64) will increase coverage by 0.04%.
Report is 2 commits behind head on main.
The diff coverage is 95.45%.

@@             Coverage Diff              @@
##               main    #8938      +/-   ##
============================================
+ Coverage     71.08%   71.13%   +0.04%     
- Complexity    57276    57281       +5     
============================================
  Files          4758     4759       +1     
  Lines        269869   269881      +12     
  Branches      39487    39488       +1     
============================================
+ Hits         191836   191970     +134     
+ Misses        61891    61742     -149     
- Partials      16142    16169      +27     

Files Changed	Coverage Δ
...a/org/opensearch/common/xcontent/XContentType.java	100.00% <ø> (ø)
...ava/org/opensearch/transport/TransportService.java	80.14% <ø> (+0.32%)	⬆️
...rg/opensearch/core/xcontent/MediaTypeRegistry.java	85.29% <92.30%> (ø)
.../opensearch/client/indices/CreateIndexRequest.java	77.77% <100.00%> (+1.11%)	⬆️
...g/opensearch/client/indices/PutMappingRequest.java	72.41% <100.00%> (ø)
.../opensearch/core/common/io/stream/StreamInput.java	88.64% <100.00%> (ø)
...n/java/org/opensearch/core/xcontent/MediaType.java	100.00% <100.00%> (ø)
...ensearch/common/xcontent/spi/XContentProvider.java	100.00% <100.00%> (ø)
.../java/org/opensearch/rest/AbstractRestChannel.java	90.69% <100.00%> (ø)

... and 472 files with indirect coverage changes

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: SUCCESS ✅
• URL: https://build.ci.opensearch.org/job/gradle-check/21192/
• CommitID: c69ec94

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/21194/
• CommitID: d64bef5
  Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green.
  Is the failure a flaky test unrelated to your change?

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/21199/
• CommitID: d64bef5
  Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green.
  Is the failure a flaky test unrelated to your change?

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: SUCCESS ✅
• URL: https://build.ci.opensearch.org/job/gradle-check/21202/
• CommitID: d64bef5