Related to #6035
This implements the keybind/action portion of #5974 so that this can
have a binding and so that other apprts can respond to this and
implement it this way.
I make the following suggestion through a PR since I already tried this locally and have a branch ready:
- Rename Split Horizontally to Split Right
- Rename Split Vertically to Split Down
Rationale:
The terms horizontal and vertical are ambiguous in the context of splitting (does it mean the splitter is vertical, or are the panes organized vertically?)
Different apps pick different interpretations, so people get confused.
IntelliJ made the same change as above based on user feedback: https://youtrack.jetbrains.com/issue/IJPL-130991/Split-Vertically-and-Split-Horizontally-are-ambiguous-and-should-be-renamed
Ghostty is using the left/right nomenclature in other menu items. In the codebase, SplitDirection is already left/right.
Fixes#1389
This is just a fun AppKit quirk. This menu item is set automatically
based on the keyboard shortcut (apparently) and when its overwritten
then its gone forever. So, let's just not set it.
