ART: Add GetClassMethods

Add GetClassMethods support. Add a test.

Bug: 31684578
Test: m test-art-host-run-test-912-classes
Change-Id: I7f063806671db5a5a69f7064e61f950b246f0b86
diff --git a/runtime/openjdkjvmti/OpenjdkJvmTi.cc b/runtime/openjdkjvmti/OpenjdkJvmTi.cc
index 98c4c3a..5283919 100644
--- a/runtime/openjdkjvmti/OpenjdkJvmTi.cc
+++ b/runtime/openjdkjvmti/OpenjdkJvmTi.cc
@@ -553,7 +553,7 @@
                                     jclass klass,
                                     jint* method_count_ptr,
                                     jmethodID** methods_ptr) {
-    return ERR(NOT_IMPLEMENTED);
+    return ClassUtil::GetClassMethods(env, klass, method_count_ptr, methods_ptr);
   }
 
   static jvmtiError GetClassFields(jvmtiEnv* env,