This adds the shortcut `cmd/ctrl + alt + enter` to the search modal to open a found file in a new leaf. I used the term "split" in user-facing text, because I think that's the more common
Some things to note:
- This function ignores the existing "open in new pane by default" setting.
- It also does not check to see if the file is already open. It will continue opening the value in a new split as often as the user wants.
