Add alert on preview when using /rebase quick action
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From https://gitlab.com/gitlab-org/gitlab/-/issues/372769/#note_1237538581
### Issue
If an MR reviewer uses the `/rebase` quick action and the project has "Prevent approvals from users who add commits" enabled, they are no longer able to approve or merge.
### Proposal
Show a warning on `Preview` if someone is about to use `/rebase` and the project has "Prevent approvals from users who add commits" enabled.
Similar to:

Text proposal:
> Using the rebase quick action will prevent you from approving or merging this merge request
issue