Change: File actions now always behind three dots button

The inline file actions button didn't look very nice and made the UI look cluttered.
This change hides them behind a three dots button on the line, the same that was already visible in responsive mode.
The three dots button also now has no more border and looks nicer.

https://github.com/owncloud/web/pull/2974
https://github.com/owncloud/web/issues/2998
