Publish plugin zips to maven repo

[prudhvigodithi]

Description

With existing setup the plugin jars are only published to maven repo, but not the generated plugin zips.

Related META issue

opensearch-project/opensearch-build#1916

Current Behavior

Existing all maven publications target the jar files to publish to maven, but not the generated distribution zips.

Expected Behavior

Along with plugin jars, plugin zips should also be published to maven repo with right maven coordinates, so user can download these plugins using dependancy model.

Steps To Reproduce

1. Run the gradle assemble task that outputs jar and zips.
2. Using build setup the jars are published to local staging maven repo.
3. Zip's are just added to distribution's folder during build runtime.
4. Finally once build is done, just the jar files are added to local maven repo and updates to the manifest file, but not the zips.

Proposed solution

A custom gradle plugin solution that can create the publication task for the zips to get published to local staging maven repo with right maven coordinates.
Add/Configure the custom gradle plugin openseearch.pluginzip to the gradle project and test the generated plugin zip's to upload to local maven repo.
More details on how to use the Plugin:
https://github.com/opensearch-project/opensearch-plugins/blob/main/BUILDING.md#opensearchpluginzip

[downsrob]

I raised the PR to add opensearch.pluginzip to index management, but as I noted in the meta issue here I am holding off on adding in the custom build.sh script as I believe we should continue using the default build script and then the default script should be updated after plugins have on-boarded.