A tiling window manager is driven from the keyboard, and the first thing a key
has to do is move the focus. `komorebic focus left|right|up|down` gives the
focus to the window whose tile is on that side of the focused one, as the layout
sees it, and `komorebic cycle-focus next|previous` to the next or the previous
window in the workspace's order, wrapping around. Neither moves a window: the
focus changes, the tiles stay.
The pointer follows the focus, through KWin's "Move Mouse to Focus", unless
`mouse-follows-focus disable` (or `toggle-mouse-follows-focus`) says not to.
Focusing towards a side with no window fails and changes nothing. Crossing into
the next monitor, as komorebi does on the other platforms, comes with more than
one monitor; so do eager-focus and the parts that depend on the monocle,
maximized and floating windows.
The VM test now drives the focus with komorebic in a real KWin and checks that
KWin and komorebi agree on the focused window afterwards.
