Remove mirror:: and ArtMethod deps in utils.{h,cc}

The latest chapter in the ongoing saga of attempting to dump a DEX
file without having to start a whole runtime instance.  This episode
finds us removing references to ArtMethod/ArtField/mirror.

One aspect of this change that I would like to call out specfically
is that the utils versions of the "Pretty*" functions all were written
to accept nullptr as an argument.  I have split these functions up as
follows:
1) an instance method, such as PrettyClass that obviously requires
this != nullptr.
2) a static method, that behaves the same way as the util method, but
calls the instance method if p != nullptr.
This requires using a full class qualifier for the static methods,
which isn't exactly beautiful.  I have tried to remove as many cases
as possible where it was clear p != nullptr.

Bug: 22322814
Test: test-art-host
Change-Id: I21adee3614aa697aa580cd1b86b72d9206e1cb24
diff --git a/runtime/jni_internal_test.cc b/runtime/jni_internal_test.cc
index fbd670c..61208e1 100644
--- a/runtime/jni_internal_test.cc
+++ b/runtime/jni_internal_test.cc
@@ -58,7 +58,7 @@
   void ExpectException(jclass exception_class) {
     ScopedObjectAccess soa(env_);
     EXPECT_TRUE(env_->ExceptionCheck())
-        << PrettyDescriptor(soa.Decode<mirror::Class>(exception_class));
+        << mirror::Class::PrettyDescriptor(soa.Decode<mirror::Class>(exception_class));
     jthrowable exception = env_->ExceptionOccurred();
     EXPECT_NE(nullptr, exception);
     env_->ExceptionClear();