Command assign-reviewers should wait for checks by default

[ferreiratiago]

Is your feature request related to a problem? Please describe.
Currently the reviewpad command assign-reviewers does a direct assignment of the reviewers. It would be great if we could add intelligence to the commands such as waiting for the pull request checks to be all green.

Describe the solution you'd like
The reviewpad command assign-reviewers should, by default, wait for all checks to be green before executing the assignment.

If any of the checks fail, reviewpad should provide feedback as a comment in the pull request.

When running the command, reviewpad should provide feedback while waiting for the checks to fininsh.

Here's an idea of the timeline of the events:

1. User comments /reviewpad assign-reviewers
2. Pull request has checks?
   • Yes
     • Any check failed - comment that the command will not be executed.
     • Any check in progress - comment the command will run once all checks passed.
     • All checks passed - run the command and comment the output of the execution.
   • No - Then reviewpad executes the command and comments the executing output on the pull request.

Force (--force / -f)

The user should be able to force the execution of the command, regardless of the checks. For that, we need to add the flag --force or -f that will run the command ignoring the status of the checks.