IntelliJ-Plugin: add support for other namespaces

[Der-Kai-T]

I'm currently working on some datapacks that add custom recipes for the create-mod. The IntelliJ-IDE notes that the type create:milling isn't valid. And I was not able to figure out how I can import types from other mods/namespaces.

[Jaffe2718]

At present, this function is not supported, because the embedded data pack of mod is different from the pure data pack, and there is no pack.mcmeta file. There are special plug-ins for mod development, and if you want to separate the data packs embedded in mod, you can copy these files manually.