UI Overhaul

[ybettles]

A complete UI overhaul:

• Added splash screen, which the game loads into before the main menu (currently player still loads in here but that will be fixed later)
  
• Moved the main menu, pause, and splash plugins into a module called ui
  • helpfully, we can now include UI by just using the UIPlugin
• Made some helpful structs with pre-made things like buttons and menu containers, so implementing new pieces of menu UI is way simpler and less verbose
• Added a Quit to Title button to the Pause menu
  
• Figured out what was up with my button colors, so we have nice green buttons now
• Sorted out centralising the logic that listens for press of Esc so that we aren't repeating the same listener code everywhere (and it's easier to maintain bc it's in one place instead of like six)
• Made the menus have grey translucent background to make it clearer when the game is paused that the entities in the background will not be interactive while paused (see second screenshot)
• Documented the heck out of it all so hopefully it is easier to use and understand

✨ woohooooo! :))

[ybettles]

Realising that "Quit to Title" doesn't work quite as intended because it implies ending the current game, which it currently does not do. I think I need to add a GameState::End state or something, so that it can transition into that, do some cleanup (involves tagging things with OnGameScreen in order to do that), and then return to the main menu. Then on entering GameState::Game after that, we'd need to perform some checks for whether stuff already exists, (maybe we have some resource that has a boolean to reflect whether or not there is a game in progress already?) and if it doesn't, it sets up the playing field with a new game setup. (Kinda just thinking out loud but seemed sensible to write it down lol)

[signal32]

omg this is amazing!!! its so neat and organized now! ive even learned about a few new rust things and seen some genuinely cool new approaches to solving problems i would not have thought of before :))
left a bunch of comments but am genuinely very happy with this even as is ✨