This adds some new special case handling for key sequences when an
unbound keyboard input is received. If the current keybinding set scope
(i.e. active tables) has a `catch_all` binding that would `ignore`
input, then the entire key sequence is dropped.
Normally, when an unbound key sequence is received, Ghostty encodes it
and sends it to the running program.
This special behavior is useful for things like Vim mode which have `g>g`
to scroll to top, and a `catch_all=ignore` to drop all other input. If
the user presses `g>h` (unbound), you don't want `gh` to show up in your
terminal input, because the `catch_all=ignore` indicates that the user
wants that mode to drop all unbound input.
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