Add androidx Fragment support

Author: atorralba

java/ql/lib/semmle/code/java/frameworks/android/Fragment.qll

@@ -4,7 +4,9 @@ import java
 
 /** The class `android.app.Fragment`. */
 class AndroidFragment extends Class {
-  AndroidFragment() { this.getAnAncestor().hasQualifiedName("android.app", "Fragment") }
+  AndroidFragment() {
+    this.getAnAncestor().hasQualifiedName(["android.app", "androidx.fragment.app"], "Fragment")
+  }
 }
 
 /** The method `instantiate` of the class `android.app.Fragment`. */

java/ql/test/library-tests/frameworks/android/fragments/TestFragment.java

@@ -0,0 +1,6 @@
+import androidx.fragment.app.Fragment;
+
+public class TestFragment extends Fragment {
+    class SecondFragment extends android.app.Fragment {
+    }
+}

java/ql/test/library-tests/frameworks/android/fragments/options

@@ -0,0 +1 @@
+//semmle-extractor-options: --javac-args -cp ${testdir}/../../../../stubs/google-android-9.0.0

java/ql/test/library-tests/frameworks/android/fragments/test.expected

@@ -0,0 +1,2 @@
+| TestFragment.java:3:14:3:25 | TestFragment |
+| TestFragment.java:4:11:4:24 | SecondFragment |

java/ql/test/library-tests/frameworks/android/fragments/test.ql

@@ -0,0 +1,6 @@
+import java
+import semmle.code.java.frameworks.android.Fragment
+
+from AndroidFragment f
+where f.getFile().getBaseName() = "TestFragment.java"
+select f