ci: Add GitHub token permissions for workflows (#34122)

Summary:
This PR adds minimum token permissions for the GITHUB_TOKEN using https://github.com/step-security/secure-workflows.

GitHub recommends defining minimum GITHUB_TOKEN permissions for securing GitHub Actions workflows
- https://github.blog/changelog/2021-04-20-github-actions-control-permissions-for-github_token/
- https://docs.github.com/en/actions/security-guides/automatic-token-authentication#modifying-the-permissions-for-the-github_token
- The Open Source Security Foundation (OpenSSF) [Scorecards](https://github.com/ossf/scorecard) treats not setting token permissions as a high-risk issue

This project is part of the top 100 critical projects as per OpenSSF (https://github.com/ossf/wg-securing-critical-projects), so fixing the token permissions to improve security.

Signed-off-by: Varun Sharma <[email protected]>

## Changelog
[General] [Security] - Add GitHub token permissions for workflows
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Pull Request resolved: https://github.com/facebook/react-native/pull/34122

Test Plan: N/A

Reviewed By: cipolleschi

Differential Revision: D37597988

Pulled By: cortinico

fbshipit-source-id: 2f45914e2202a7b5bf7fa60b019dd12cdcf31952