Add option to remove obsolete drafts

[milhnl]

Hi all!

This is an updated version of https://github.com/pazz/alot/pull/1313 (which aimed to fix https://github.com/pazz/alot/issues/1044). I rebased the commit, and deduplicated the code in SaveCommand and SendCommand. I think that was the most obvious feedback then, but I can imagine there's more.

[milhnl]

By the way, I just remembered I saw a pull request today that I think was merged which made the tags to indicate a draft configurable by the user. That is not yet incorporated in this commit.

[guludo]

I took a look at adding support for the draft_tags stuff here and it seems there are other places in the current code base that needs the same type of fix already (see the output of git grep -W -e "'draft'" -e '"draft"' upstream/master)...

[pazz]

Sorry for the late response but what is the status of this?

[milhnl]

No worries. I'm busy with some IRL stuff right now, but have an idea on how to fix the draft_tags situation. It boils down to also using the full list to select drafts, but it is probably clearer as a commit. I think I can get y'all a revised pull request somewhere in the coming month.