applets/mediacontroller: Increase visibility of the Raise action

Let the raise action show on the systray header and make its text more clear.

Follow-up to: !2366 (merged) Alternative to: !1000 (closed)

Some concerns to be addressed/considered before merging this:

@nicolasfella:

What exactly happens on open is up to the player. It could be that your player simply doesn't implement it at all

Even if it is implemented activation can't work as expected on Wayland because the interface is missing a way to pass an activation token: https://gitlab.freedesktop.org/mpris/mpris-spec/-/issues/18

@ngraham:

Still, the fact that it doesn't work at least for Elisa will become more obvious with the UI to trigger this feature no longer hidden only in a context menu. So we should put some work into fixing it, yeah.

Hiding on Wayland would be an option, albeit a sad one.