[DRAFT] Created new ReplicaShardBatchAllocator

[shiv0408]

to be used instead of ReplicaShardAllocator for batch calls

Description

Sub PR part for overall improvement of #5098

• RSA change as per [Enhancement] Add a batch allocator for building allocation decisions for multiple primary & replica shards #8960

Note :

1. UTs and ITs will be added in upcoming commits.
2. Gradle check will fail on compilation because this PR is dependent on multiple other PRs
3. Not creating a helper class for common code as old PrimaryShardAllocator class will be deprecated in future.
4. Most of the code is copy pasted from PrimaryShardAllocator class, only changes are handling of multiple shards metadata and handling of single DiscoveryNode object in response for a batch of shards.
5. CHANGELOG will be updated only after last PR is raised(being merged) for this project.

Related Issues

Resolves #8960

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/21260/
• CommitID: 0d0e5c2
  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?