Slightly Better Foliage Colors

((previous versions were hosted on another site))

• Updated pack_format to 18.
• Added "supported_formats" field to pack.mcmeta, allowing the pack to be compatible with 1.20.2, 1.20.3, and 1.20.4.
• Short Grass now works correctly in game versions 1.20.3+. (Added JSON)
• Tweaked one of the colors on the Dark Oak Leaves texture slightly. (Edited texture)
• Grass Blocks in Item form now use Forest colors like on Bedrock Edition. (Added textures, edited JSON)