Access Widener 2.0 with support for Transitive Access Wideners (#484)

* Added global access widener support.

* Adapt loom to changed API of latest AW PR.

* Fix expected access widener to fix the test. Since the access widener is now streamed directly into the writer, the expanded rules (i.e. accessible field makes the owning class also accessible) are no longer found in the remapped file.

* Add basic transitive accesswidener test

* Extracted applying transitive access wideners into their own jar processor since they also need to be applied if there is no AW in the mod itself.

* Misc assortment of fixes

* Set up the processor lazily to allow for adding the intermediary MC jar, which is needed to correctly remap intermediary AWs to named.

* Rework to setup the tiny remapper classpath with the mc jar
Add an extension prop to disable

* Add TransitiveDetectorVisitor

* Minor refactoring.

* Use release-version of access-widener.

Co-authored-by: modmuss50 <modmuss50@gmail.com>

src/main/java/net/fabricmc/loom/api/LoomGradleExtensionAPI.java

@@ -204,4 +204,11 @@ public interface LoomGradleExtensionAPI {
 	 * @return the version defined in the fabric.mod.json
 	 */
 	String getModVersion();
+
+	/**
+	 * When true loom will apply transitive access wideners from compile dependencies.
+	 *
+	 * @return the property controlling the transitive access wideners
+	 */
+	Property<Boolean> getEnableTransitiveAccessWideners();
 }