Clicking on desktop notifications sent by Ghostty _should_ cause the
window that sent the notification to come to the top. However, because
the notification that was sent targeted the wrong surface (apprt surface
vs core surface) and the window did not call `present()` on itself the
window would never be brought to the surface, the correct tab would not
be selected, etc.

Fixes #9145

Fixes #8991

Uses OSC 133 esc sequences to keep track of how long commands take to
execute. If the user chooses, commands that take longer than a user
specified limit will trigger a notification. The user can choose between
a bell notification or a desktop notification.

Some bell features should be triggered on the receipt of every BEL
character, namely `audio` and `system`. However, Ghostty was setting a
boolean to `true` upon the receipt of the first BEL. Subsequent BEL
characters would be ignored until that boolean was reset to `false`,
usually by keyboard/mouse activity.

This PR fixes the problem by ensuring that the `audio` and `system`
features are triggered every time a BEL is received. Other features
continue to be triggered only when the `bell-ringing` boolean state
changes.

Fixes #8957

Attempts a resolution for
https://github.com/ghostty-org/ghostty/discussions/8572

This matches the behavior of the old GTK apprt where
unfocused-split-fill /opacity doesn't apply when there is only one
active surface.