Place the user actions in a dropdown window with labels

[Paul-Etienne]

This is built on top of @awestm 's PR regarding issue #13991.
It places the action buttons rack inside of a dropdown window as done originally by awestm, for both desktop and mobile, as I figured even desktop would benefit from this redesign. The original problem was that these buttons are very confusing without hovering over them, and displaying the full text next to the icon is the most efficient way to get that information.
But since showing the text for all of the buttons takes too muhc space even on desktop, the best thing to do (in my opinion) is use the dropdown for all situations.
I would post screenshots but somehow I've broken my local environment and don't have time to set it back up right now.

I placed the dropdown button on the same line as the user's name as it makes more sense now, since it's related to the user's profile. I also fixed the opacity and font-size for the "last active since" text. The opacity would cause this text to overlap the dropdown window (and was looking odd there to be honest, being slightly transparent and smaller than the beginning of the sentence).

[ornicar]

Interesting, but from a quick try there seems to be issues atm

[Paul-Etienne]

Thanks for pointing that out, I'll check that when I have time

[Paul-Etienne]

Alright, I believe I've fixed the issues you reported @ornicar. I had only tested on the user's own profile 🤦‍♂️
I've put the dropdown menu on the second line again, I didn't think there could be other ui components at this location.
But there's still some gray area, I see code in def mini() in RelationUi.scala that would probably break because of the remaining btn-rack classes, but I'm not sure where it's called exactly.

[Paul-Etienne]

Do you see other things that need to be addressed in this PR?