Add command for tagging commit

[cruessler]

Opened as a draft for getting early feedback.

Open questions:

• Do you want to validate the tag before calling repo.tag or do you want
  to rely on git refusing invalid tags?
• Should the dialog have just a single line?

Will close #103.

[extrawurst]

@cruessler thanks for tackling this.

Do you want to validate the tag before calling repo.tag or do you want
to rely on git refusing invalid tags?

I would rely on git refusing an invalid tag. we have a reusable error message box for that already.

Should the dialog have just a single line?

Not exactly sure what you mean? I would expect the same dialog we already use for the stash-name.

edit: you can run - the currently failing - clippy checks locally by simply using make check (combining fmt check and clippy)

[cruessler]

@extrawurst Thanks for the feedback! I have incorporated it and am now able to locally tag commits. The revlog does not update, though, after a commit is tagged and I have found no way to change that. InternalEvent::Update(NeedsUpdate::ALL) is pushed to the queue after the commit is tagged. Am I missing something?

[extrawurst]

@cruessler I could help you more when you would push those changes you made :)

edit: just checked, new tags were never picked up in the revlog, has nothing todo with your PR: #190

[extrawurst]

@cruessler as of #195 new tags will be refetched every 2s.

when you add a tag you can also force a refetch (because we know a new one is gonna be there) in Revlog:

self.git_tags.request(Duration::from_secs(0), true)?;

[cruessler]

@extrawurst I updated the branch with your feedback. I did not need to explicitly ask the Revlog to re-load the tags, they showed up immediately.

[extrawurst]

@cruessler nice work! thank you! ❤️