Update: Analog controls & skip button

Added a few handy things today:

1. Analog controls now work, so it's playable on Steam Deck with default controls.

2. Skip button can be clicked and held or just hold down Space/A-Button/B-Button to skip the intro. 

3. Music kicks in when the player starts the running sequence

All small parts, but I've learned a bit more about how Godot handles UI, how to do progress bars, write custom signals and add input mapping. It also feels a teensy bit more polished (though still very rough!). Hoping the skip button will speed up testing a bit too.