add mcdev imports file

build-data/mcdev-imports.txt

@@ -0,0 +1,4 @@
+# You can use this file to import files from vanilla into the project
+# both fully qualified and a file based syntax are accepted here:
+# net.minecraft.world.level.entity.LevelEntityGetterAdapter
+# net/minecraft/world/level/entity/LevelEntityGetter.java