[REQ] Make custom modding of common resources easier

[pizzaboxer]

Acknowledgement of preliminary instructions

• [X] I have read and acknowledged the preliminary instructions.

What idea do you have?

Instead of vaguely hinting at where the files should be placed, we should make it a lot easier to just let the user choose a file and handle it from there, much like how choosing a font works.

Mouse cursors, shift lock cursor, avatar background rbxl, anything else?