Move HandleCache to HGraph.

This avoids passing the `VariableSizedHandleScope*` argument
around and eliminates HGraph::inexact_object_rti_ and its
initialization. The latter shall allow running Optimizing
gtests that do not require type information without creating
a Runtime in future. (To be implemented in a separate CL.)

Test: m test-art-host-gtest
Test: testrunner.py --host --optmizing
Test: aosp_taimen-userdebug boots.
Change-Id: I36fe9bc556c6d610d644c8c14cc74c9985a14d64
19 files changed