Add extensions to gradle plugin

[ryanbogan]

Description

In order to run integration testing for the SDK and future extensions, the OpenSearch gradle plugin needs to be able to run both extensions and plugins at the same time. This PR adds the capability to run extensions from the gradle plugin, while leaving all existing plugin functionality untouched.

Issues Resolved

opensearch-project/opensearch-sdk-java#589

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.

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/14241/
• CommitID: 309d56e
  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/14245/
• CommitID: bc7e6ab
  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?

[ryanbogan]

This doesn't only affect extensions, so should I add a changelog entry?

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/14335/
• CommitID: dd2ca00
  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/14336/
• CommitID: 5c24aaf
  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/14337/
• CommitID: 1ecb4ab

[dblock]

LGTM!

Looking at this code, I am wondering whether we should extract the connectivity parts of an extension into an interface? I suspect that for in-proc we will not want host/port as a communication channel. WDYT?

[saratvemulapalli]

@owaiskazi19 Ryan addressed the comments, could you take a look again?

[saratvemulapalli]

LGTM!

Looking at this code, I am wondering whether we should extract the connectivity parts of an extension into an interface? I suspect that for in-proc we will not want host/port as a communication channel. WDYT?

Makes sense. Definitely they have to be APIs. And abstract out inner structures. We started with something very simple, its about time to build these changes.

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: SUCCESS ✅
• URL: https://build.ci.opensearch.org/job/gradle-check/14699/
• CommitID: 1458858

[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-7235-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 84d66e091a3dc4c52f72f64b3bbd2d45580feb48
# Push it to GitHub
git push --set-upstream origin backport/backport-7235-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-7235-to-2.x.