Drop docked mode status icon in top bar

As mentioned here, I don't think the docked mode status icon is necessary and could be removed.

Since docked or not influence the way objects are placed on screen, whether windows have close buttions and (soon) which apps are being displayed i think we need a way for the user to figure out the current mode of operation. If there's a better way than showing the icon i'm all ears.

@tobias.bernard ping? We can drop the icon (we have the quick setting) but i'm unclear what the criterias are for things to end up in the top bar or not.

Issue moved to https://gitlab.gnome.org/World/Phosh/phosh/issues/542

closed