Since there is no way to map a connector to a Gdk Window ID and window
ID's are not static per monitor, the entire Window and Wayland system
has been rewritten to store a "target monitor" connector name, which is
the name of the monitor we want to be on. Every time a monitor is
removed or added, it is checked against the monitors of our Wayland
backend to match connector to Gdk ID and then the Window is
created/destroyed on the window(The target monitor is preferred, but if
it doesn't exist, other monitors are used too).
This is not perfect, since the matching of connector name to Gdk ID is
only an approximation of the Gdk behaviour (Especially rough
on hyprland with the headless monitor. A hack is needed to handle that).
Additionally the monitor can now be specified by connector name when
starting up (e.g. "gBar bar DP-1").
gBar no longer crashes when it's monitor is removed and is instead
evacuated onto another monitor or the next monitor added. We don't
change any monitor indices etc., which results in some glitchy results
LAYER_TOP (The previously hardcoded layer) draws below fullscreen
windows (at least on Hyprland). For the flyin we want it to be always on
top, so LAYER_OVERLAY is used instead now.
