Additional options for dimension effects RE: 25w07a core shader changes

Recent changes to core shaders in 25w07a have broken several "very cool Resource Pack features" which do indeed "lack supported alternatives" - namely, the ability to "add" new sun and moon textures to datapack-defined dimensions by overriding the position_tex_color core shader.

Currently, this works by checking the fog color of the current biome and modifying the texture coordinates of the sun and moon elements accordingly. But as of recently, FogColor is no longer passed to these elements, requiring the FogColor uniform to be re-added to the JSON definitions, which, as of snapshot 25w07a, is impossible, as JSON definitions have been removed entirely. This may create issues for several fairly popular datapacks including The Expansion and the Bracken Pack, which employ this workaround.

Since reverting the changes is likely not on the table, I propose expanding the "effects" field in the dimension_type definition. Currently, the field accepts a string: "overworld", "the_nether", or "the_end"; this could be expanded to specify assets for the sun, moon, and clouds (for the overworld) and the skybox (for the End) the same way assets are specified for trims, paintings, etc. For example:

"effects": "minecraft:overworld"

becomes

"effects": {
 "type": "minecraft:overworld", 
  "assets": {
   "sun": "minecraft:environment/sun",
   "moon": "minecraft:environment/moon_phases",
   "clouds": "minecraft:environment/clouds"
  }
}

This would significantly reduce reliance on "unsupported" shader tricks.