Move gui textures to gui folder

[DMgaming100]

Version Information

6ed5986

Log or Crash Report

No response

Reproduction steps

• Refinery gui is messed up

• Move the slot/ folder to gui/slot/

• Make all the slots in the machines use slot textures from gui/slot/ instead of being baked into the texture

• Split solar_panel/default_solar_panels to 3 textures in gui/solar_panel/

• Make solar panel use the planet textures from gui/celestialbodies/ instead of solar_panel/default_light_sources & solar_panel/moon_light_sources