Forgix should ignore files in data, config, and assets folders

[cassiancc]

This aims to fix #30 and #33 by having Forgix ignore files in data, assets, and config directories. Open to feedback of course, but some resolution is necessary as without a fix like this one mods that provide worldgen files like Infinite Dimensions are unusable with Forgix, as it detects the data key as if it was a mixin.

[cassiancc]

An example file in the config folder that caused Forgix to detect it as a mixin.

{
	"feature": "infinity:all_trees",
	"placement": [
		{
			"count": {
				"type": "minecraft:weighted_list",
				"distribution": [
					{
						"data": 6,
						"weight": 9
					},
					{
						"data": 7,
						"weight": 1
					}
				]
			},
			"type": "minecraft:count"
		},
		{
			"type": "minecraft:in_square"
		},
		{
			"type": "minecraft:surface_water_depth_filter",
			"max_water_depth": 0
		},
		{
			"heightmap": "OCEAN_FLOOR",
			"type": "minecraft:heightmap"
		},
		{
			"type": "minecraft:biome"
		}
	]
}