Fixes a regression where `C-S-c` stopped working properly in both legacy
and Kitty modes (although the Kitty mode side only affected alternates
and not the key itself so it probably worked fine in most programs).
The issue is that `charactersIgnoringModifiers` changes behavior if
`control` is pressed, so it doesn't really ignore all modifiers. We have
to use `characters(byApplyingModifiers:)` to get the proper unshifted codepoint
when `control` is pressed.
Fixes#7131
Regression from #7121
Our consumed mods should not include "alt" if `macos-option-as-alt` is
set. To do this, we need to calculate our consumed mods based on the
actual translation event mods (if available, only available during
keyDown).
This is a large refactor of the keyboard input handling code in
libghostty and macOS. Previously, libghostty did a lot of things that
felt out of scope or was repeated work due to lacking context. For
example, libghostty would do full key translation from key event to
character (including unshifted translation) as well as managing dead key
states and setting the proper preedit text.
This is all information the apprt can and should have on its own.
NSEvent on macOS already provides us with all of this information,
there's no need to redo the work. The reason we did in the first place
is mostly historical: libghostty powered our initial macOS port years
ago when we didn't have an AppKit runtime yet.
This cruft has already practically been the source of numerous issues, e.g.
#5558, but many other hacks along the way, too.
This commit pushes all preedit (e.g. dead key) handling and key translation
including unshifted keys up into the caller of libghostty.
Besides code cleanup, a practical benefit of this is that key event
handling on macOS is now about 10x faster on average. That's because
we're avoiding repeated key translations as well as other unnecessary
work. This should have a meaningful impact on input latency but I didn't
measure the full end-to-end latency.
A scarier part of this commit is that key handling is not well tested
since its a GUI component. I suspect we'll have some fallout for certain
keyboard layouts or input methods, but I did my best to run through
everything I could think of.
