Add auto backport functionality to backport PRs for releases #205
Description
Coming from meta issue opensearch-project/opensearch-plugins#108:
- Add auto-backport PR creation Github action to make sure all the PRs are backported for a particular release.
- Add auto-delete for merged auto-backport PRs to clean up the branches created during auto-backport.
- Add documentation for the same.
Related documentation: https://github.com/opensearch-project/opensearch-plugins/blob/main/BACKPORT.md