Rename wp-cli commands

[MARQAS]

Description of the Change

This PR is used to rename the WP-CLI commands as requested in #2981

Closes #2981

How to test the Change

• Run the old WP-CLI commands, they will give a deprecation warning along with the expected output
• Run the renamed commands, they will give the expected output

Changelog Entry

Added - get-cluster-indices, get-indices, sync, clear-sync, get-ongoing-sync-status, get-last-cli-sync, stop-sync WP-CLI commands Deprecated - get-cluster-indexes, get-indexes, index, clear-index, get-indexing-status, get-last-cli-index, stop-indexing WP-CLI commands

Credits

Props @MARQAS

Checklist:

• [x] I agree to follow this project's Code of Conduct.
• [x] I have updated the documentation accordingly.
• [ ] I have added tests to cover my change.
• [ ] All new and existing tests pass.