ART: Add GetAllThreads

Add support for GetAllThreads. Add a test.

Bug: 31684593
Test: m test-art-host-run-test-924-threads
Change-Id: I7068dd4d3700a32a87a44d38590e53df0bd238c7
diff --git a/runtime/openjdkjvmti/OpenjdkJvmTi.cc b/runtime/openjdkjvmti/OpenjdkJvmTi.cc
index 4334ca3..e41f074 100644
--- a/runtime/openjdkjvmti/OpenjdkJvmTi.cc
+++ b/runtime/openjdkjvmti/OpenjdkJvmTi.cc
@@ -127,7 +127,7 @@
   }
 
   static jvmtiError GetAllThreads(jvmtiEnv* env, jint* threads_count_ptr, jthread** threads_ptr) {
-    return ERR(NOT_IMPLEMENTED);
+    return ThreadUtil::GetAllThreads(env, threads_count_ptr, threads_ptr);
   }
 
   static jvmtiError SuspendThread(jvmtiEnv* env, jthread thread) {