[autoscaler] Add CloudWatch related config files update support

[Zyiqin-Miranda]

Why are these changes needed?

These changes add a set of improvements to enable automatic update of user customized CloudWatch related configuration json files (agent, dashboard, alarm) during ray up process.

Related issue number

https://github.com/ray-project/ray/issues/8967

Checks

• [x] I'm working against the latest source on the experimental branch.
• [x] I've run scripts/format.sh to lint the changes in this PR.
• [ ] I've included any doc changes needed.
• [ ] I've made sure the tests are passing. Note that there might be a few flaky tests.
• Testing Strategy
  • [x] Unit tests
  • [ ] Release tests
  • [ ] This PR is not tested :(

License

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.