Add an option to show the server sidebar in compact mode

[Calman102]

Or dynamically depending on the width of window.

[BreeceW]

I would want it to depend on the window width. But my question is if you click on a server icon in this half-open state, should it expand the menu or just go to that server. If the latter, what if there is no selected channel in that server yet?

[Calman102]

Simply expanding the menu is fine.