A whole bunch of inputd improvements

• Bunch of refactors and cleanups.
• Automatically switch to the first vt upon creation rather than forcing either vesad or fbbootlogd to activate it.
• Have a single global graphics driver rather than a per-vt graphics driver. The latter is a remnant from back when virtio-gpud would deactivate itself to switch back to vesad when switching away from vt 3 running orbital.

This also makes it easier to in a future MR create vt's on the fly when a consumer needs one as opposed to creating them in advance in the graphics driver, which has several advantages.