Delete outdated spell check comment when new commits are pushed in a pull request

[BrettDong]

Summary

None

Purpose of change

Although there is a mechanism to prevent spell checker from posting duplicate comments in a pull request, it can still create excessive amount of comments when the sentences containing the typos are updated in subsequent commit pushes, but typos themselves still exist, like in #56413. It would look cleaner if previous outdated spell check comments are automatically deleted when posting a new one.

Describe the solution

When spell check completes,

1. If an exact same spell check comment already existed, just do nothing and exit the workflow
2. Remove previous spell check comments
3. Post the new spell check comment

Describe alternatives you've considered

Testing

Not tested.

Additional context