Official Mojang Mappings support

# Please read and understand the EULA before using!

Use in your build.gradle with the following:

`mappings minecraft.officialMojangMappings()`

To automatically migrate to Mojang mappings run the following:

`gradlew.bat migrateMappings --mappings "net.mojang.minecraft:mappings:1.16.2"`

Co-authored-by: Ramid Khan <ramidzkh@gmail.com>

src/main/java/net/fabricmc/loom/util/DependencyProvider.java

@@ -133,6 +133,10 @@ public abstract class DependencyProvider {
 		}
 
 		public Set<File> resolve() {
+			if (dependency instanceof SelfResolvingDependency) {
+				return ((SelfResolvingDependency) dependency).resolve();
+			}
+
 			return sourceConfiguration.files(dependency);
 		}