This ports the leave room dialog to QML, everywhere. There are now no differences between the various leave dialogs.

Showing the bootstrap state and showing there are unverified devices is
still missing.

We explicitly set a parent. We can't assign to
ApplicationWindow.transientParent though, only to
Window.transientParent, so we just call setTransientParent in C++.

There are probably a few things wrong with this, but I'm going to call it good enough for an initial commit

Also fix a lot of warnings.

Copy address location -> Copy link location

fixes #291

fixes #463

fixes #499