Support `beet import --flat` and `--group-albums` while tagging

[edgar-vincent]

Hi!

As always, thanks a lot for your great work.
Do you think it would be feasible to support the --flat and --group-albums options while tagging? This would help group multiple directories together as well as split them into multiple albums.

Thanks a lot!

EV

[semohr]

Hey edgar, we already support --group-albums 🙃 You can customize the behavior of your tag button.

I will see if we can also add support for the --flat option 👍