Constant unpicking (#328)

* Start adding constant unpicking

* Update to use unpick cli

* Fix build?

* Fix?

* Fix log spam when unpicking

* Improve unpick tests

src/main/java/net/fabricmc/loom/LoomGradleExtension.java

@@ -354,6 +354,10 @@ public class LoomGradleExtension {
 		return new File(getProjectPersistentCache(), "log4j.xml");
 	}
 
+	public File getUnpickLoggingConfigFile() {
+		return new File(getProjectPersistentCache(), "unpick-logging.properties");
+	}
+
 	public ConfigurableFileCollection getLog4jConfigs() {
 		return log4jConfigs;
 	}