[FEATURE] Automate taking action on inactive maintainers

[bshien]

Is your feature request related to a problem? Please describe

When maintainers are inactive, we propose taking some action to eventually move them from the Maintainers list to the Emeritus list in MAINTAINERS.md, removing them from CODEOWNERS, and revoking their maintainer level access, but doing this manually doesn’t scale.

Describe the solution you'd like

Use the automation app to query the Metrics cluster(https://github.com/opensearch-project/opensearch-metrics) for the maintainer_engagement index and perform some automated action to kickoff moving inactive maintainers to Emeritus.

Describe alternatives you've considered

No response

Additional context

Part of opensearch-project/opensearch-metrics#57