Closes #ISSUE
Adds the ability to our JSON updating code to update arrays within other
objects. Previously updating of arrays was limited to just top level
arrays (i.e. `keymap.json`) however this PR makes it so nested arrays
are supported as well using `#{index}` syntax as a key.
This PR also fixes an issue with the array updating code that meant that
updating empty json values `""` or an empty `keymap.json` file in the
case of the Keymap Editor would fail instead of creating a new array.
Release Notes:
- Fixed an issue where keybindings would fail to save in the Keymap
Editor if the `keymap.json` file was completely empty
69a7c3e252