feat: added new workflow for issue monitoring in react native (#49225)

Summary:
While triaging issues in the React Native repository, we face two major challenges:

- Missing Issues: The large volume of issues makes it difficult to ensure that none are overlooked.
- Ownership: There is no structured process to determine who should handle which issue.

To address these challenges, we are setting up this action.

## Changelog:

<!-- Help reviewers and the release process by writing your own changelog entry.

Pick one each for the category and type tags:

[GENERAL] [ADDED] - Added a new workflow to monitor new issue in repo.

For more details, see:
https://reactnative.dev/contributing/changelogs-in-pull-requests
-->

Here we are using this github action: https://github.com/react-native-community/repo-monitor to monitor new issues and then notify it on specific discord server to notify someone.

Currently this action runs every 6 hours.

Requirements:
- We need following inputs to make this workflow run:
   -  `DISCORD_WEBHOOK_URL` to be added in secrets [Needed for posting message in specific channels]
   -  `role_id`: To notify a group.

Pull Request resolved: https://github.com/facebook/react-native/pull/49225

Test Plan: NA

Reviewed By: cipolleschi

Differential Revision: D69254130

Pulled By: cortinico

fbshipit-source-id: 43a57f8f3bf161042a9432d02f292896ea8f7622