Store minecraft jars in a maven repo instead of an ivy repo.

Improve intelij support for attaching sources.

src/main/java/net/fabricmc/loom/extension/LoomFilesBaseImpl.java

@@ -97,4 +97,14 @@ public abstract class LoomFilesBaseImpl implements LoomFiles {
 	public File getRemapClasspathFile() {
 		return new File(getProjectPersistentCache(), "remapClasspath.txt");
 	}
+
+	@Override
+	public File getGlobalMinecraftRepo() {
+		return new File(getUserCache(), "minecraftMaven");
+	}
+
+	@Override
+	public File getLocalMinecraftRepo() {
+		return new File(getRootProjectPersistentCache(), "minecraftMaven");
+	}
 }