Viewing and dropping commits in Weblate

**Is your feature request related to a problem? If so, please describe.**

Occasionally, Weblate generates commits that we don't want to merge, for example because they only contain unacceptable changes (e.g. spam or other unwelcome change), or no real changes at all (e.g. a commit that only modifies the translation file headers).

**Describe the solution you'd like**

It would be great if Weblate allowed viewing the commits in the repository, and dropping any bad one.

Dropping a commit is fairly easy to achieve with `git rebase -i`. It should be possible to automate that process by setting the `EDITOR` environment variable so that Git calls a custom script to edit the rebase commands.

**Describe alternatives you've considered**

It's possible to merge only the commits we want and then reset the Weblate repository, but this isn't very safe.

Reverting commits as discussed in #3040 is only appropriate if the changes have already been merged. I want to drop commits before they're merged so that the Git history stays clean.

**Additional context**

I don't often encounter commits that I don't want to merge, so this issue isn't high priority for me, but I wanted to share my idea on how it could be solved in a nice way.