linux: Add file_finder::Toggle key binding (#34380)

This fixes a bug on linux where repeated presses of p while holding down
the ctrl modifier navigates through options in reverse.

Closes #34379 

The main issue is the default biding of ctrl-p on linux is
menu::SelectPrevious hence in context "context": "FileFinder ||
(FileFinder > Picker > Editor)" it would navigate in reverse

Release Notes:

- Fixed `file_finder::Toggle` on Linux not scrolling forward

assets/keymaps/default-linux.json

@@ -999,6 +999,7 @@
   {
     "context": "FileFinder || (FileFinder > Picker > Editor)",
     "bindings": {
+      "ctrl-p": "file_finder::Toggle",
       "ctrl-shift-a": "file_finder::ToggleSplitMenu",
       "ctrl-shift-i": "file_finder::ToggleFilterMenu"
     }