Create: Schematic Folders

First release, for Minecraft 1.21.1 (NeoForge) with Create 6.

- Folders for schematics, encoded in the file name with a double underscore (`steam__boilers__boiler.nbt` is "boiler" in folder steam / boilers). Nothing changes on disk; removing the mod is safe.
- Schematic Table: a magnifier button opens a browser with a folder tree, the schematics of the selected folder and a search box across all folders. Double-click to select.
- Schematic and Quill: a folder bar under the save prompt to pick or add a folder, or type a path with `/` in the name. A hint shows where the schematic will be saved.
- Styled like Create's own schematic screens. English and Dutch.