fix: bring back smali files support (#961)

jadx-plugins/jadx-plugins-api/src/main/java/jadx/api/plugins/input/data/ILoadResult.java

@@ -7,4 +7,6 @@ public interface ILoadResult extends Closeable {
 	void visitClasses(Consumer<IClassData> consumer);
 
 	void visitResources(Consumer<IResourceData> consumer);
+
+	boolean isEmpty();
 }

jadx-plugins/jadx-plugins-api/src/main/java/jadx/api/plugins/input/data/impl/EmptyLoadResult.java

@@ -11,6 +11,11 @@ public class EmptyLoadResult implements ILoadResult {
 
 	public static final EmptyLoadResult INSTANCE = new EmptyLoadResult();
 
+	@Override
+	public boolean isEmpty() {
+		return true;
+	}
+
 	@Override
 	public void visitClasses(Consumer<IClassData> consumer) {
 	}