[Remote Routing Table] Initial commit for RemoteRoutingTableService setup

[himshikha]

Description

This change is for setting up base service for remote routing table operations.

• Adds interfaces for remote upload/download operations
• Adds node attributes for enabling Remote routing table repo.
• Adds FeatureFlag for Remote routing table feature to keep as experimental feature for now.

Related Issues

Resolves (#13049)

Check List

• New functionality includes testing.
  • All tests pass
• New functionality has been documented.
  • New functionality has javadoc added
• Failing checks are inspected and point to the corresponding known issue(s) (See: Troubleshooting Failing Builds)
• Commits are signed per the DCO using --signoff
• Commit changes are listed out in CHANGELOG.md file (See: Changelog)
• [ ] Public documentation issue/PR created

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[github-actions]

❌ Gradle check result for 725b2bd: FAILURE

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?

[Bukhtawar]

Directionally looks fine from keeping a separate repo and gating the feature behind a feature flag. We would need some integration and basic tests before we can consider merging this change in

[github-actions]

❌ Gradle check result for d5a17ed: FAILURE

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?

[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:

# Navigate to the root of your repository
cd $(git rev-parse --show-toplevel)
# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add ../.worktrees/OpenSearch/backport-2.x 2.x
# Navigate to the new working tree
pushd ../.worktrees/OpenSearch/backport-2.x
# Create a new branch
git switch --create backport/backport-13304-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 51214092ca532b557b6775ff8620025a51f92fcc
# Push it to GitHub
git push --set-upstream origin backport/backport-13304-to-2.x
# Go back to the original working tree
popd
# Delete the working tree
git worktree remove ../.worktrees/OpenSearch/backport-2.x

Then, create a pull request where the base branch is 2.x and the compare/head branch is backport/backport-13304-to-2.x.