added sound library settings & command (#12)

## Changes
- Added file base simple sound library
- Added base UI settings and sound library settings
- Added `play_lib_snd` command

## Notes
- The command accepts a namespace so we can leave common sound in the root folder and chapter specific sounds in its own folder

## How to test
- Run the game
- All the door sounds should play as normal.

Reviewed-on: gymkhana/gymkhana#12
Co-authored-by: oier <oierbravo@gmail.com>
Co-committed-by: oier <oierbravo@gmail.com>

gymkhana/rooms/turno_cocina/cocina_detras/esc/puerta_cocina.esc

@@ -1,3 +1,3 @@
 :action1
-play_snd res://gymkhana/sounds/cocina_detras_open.ogg
+play__lib_snd puerta_cocina_detras
 change_scene "res://gymkhana/rooms/turno_cocina/cocina/cocina.tscn"