Move ArtField to ObjPtr

Added EXPECT_OBJ_PTR_EQ and variants to gtests.

Fixed moving GC bugs in:
ClassLinker::CreatePathClassLoader
ClassLinkerTest: StaticFields

ObjPtr Decode call sites: 186 -> 181.

Some tests fail due to ResolvedFieldAccessTest, will fix in follow
up CL.

Bug: 31113334

Test: test-art-host CC baker

Change-Id: I8b266ad00f3c20c8cbe7cfdf280d175083df0b88
diff --git a/runtime/arch/stub_test.cc b/runtime/arch/stub_test.cc
index 5e39f42..432ba36 100644
--- a/runtime/arch/stub_test.cc
+++ b/runtime/arch/stub_test.cc
@@ -1688,7 +1688,7 @@
 
   EXPECT_EQ(res, reinterpret_cast<size_t>(val)) << "Value " << val;
 
-  EXPECT_EQ(val, f->GetObj(trg));
+  EXPECT_OBJ_PTR_EQ(val, f->GetObj(trg));
 }
 #endif