Adds tree fading based on camera line of sight.
Trees now fade out when they obstruct the player's view,
improving visibility.
Also includes several fixes:
- Fixes tree distribution.
- Adds a see-through shader.
- Adds camera and occlusion scripts.
Adds basic camp generation and placement logic to the map generation process.
It attempts to place the camp in a valid location, avoiding paths and water bodies. It also sets the player's spawn point to the center of the generated camp, including some basic camp props like a tent, campfire, and bed.
Additionally, vegetation spawning is now dependent on the `should_spawn_*` methods of the `CellDataResource`, allowing more control over what spawns where.
