Fixes#1802
This allows `keybind` configurations to map to any Unicode codepoint. This enables keybindings for which we don't have a registered keycode or for custom keyboard firmwares that may produce arbitrary text (but the Ghostty support is limited to a single codepoint).
The `keybind` syntax is unchanged. If a bound character doesn't map to a known logical key that Ghostty knows about, we map it to a Unicode codepoint. The unicode codepoint is compared against the _unshifted codepoint_ from the apprt key event.
Note that this binding is to a single _codepoint_. We don't support arbitrary sequences of characters or multi-code point graphemes for keybindings due to the complexity in memory management that would introduce.
This also provides a good fallback for scenarios where it might make sense to educate Ghostty about a key code or fix a bug in our keyboard input system, but the unicode data is correct. In that scenario, unicode key binds should allow key binds to still work while we investigate the input issues.
Example:
```
shift+ö=text:hello
```
This now works as expected on a US hardware keyboard with the Hungarian keyboard layout.
Fixes#872
In #867 we fixed macos-option-as-alt, but unfortunately AppKit ALSO does
some translation so some behaviors were not working correctly.
Specifically, when you had macos-option-as-alt set, option+e would
properly send `esc+e` to the pty but it would ALSO set the dead key
state for "`" since AppKit was still translating the option key.
This commit introduces a function to strip alt when necessary from the
translation modifiers used at the AppKit layer, preventing this
behavior.
Instead of making a separate enum that must be translated from the
ClipboardRequest type, simply re-use ClipboardRequest to determine the
clipboard confirmation reason.
The resizeIncrements property is only modified when the cell size of the
focused window changes. If two splits have the same cell size then the
property is not modified when focusing between the two splits.
