[vm] Unify nullability and type state among all types

This change moves 'nullability' and 'type_state' from all kinds of
types to AbstractType base class. This removes a lot of code
duplication and allows uniform access to nullability and type state
for all kinds of types.

TEST=ci
Fixes https://github.com/dart-lang/sdk/issues/47034

Change-Id: I1f0dc7fda78426db83fec6a20ebebcd632ad6d99
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/260662
Reviewed-by: Tess Strickland <sstrickl@google.com>
Commit-Queue: Alexander Markov <alexmarkov@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>

runtime/vm/raw_object_fields.cc

@@ -135,7 +135,6 @@ namespace dart {
   F(TypeArguments, nullability_)                                               \
   F(AbstractType, type_test_stub_)                                             \
   F(Type, type_test_stub_)                                                     \
-  F(Type, type_class_id_)                                                      \
   F(Type, arguments_)                                                          \
   F(Type, hash_)                                                               \
   F(FunctionType, type_test_stub_)                                             \