ART: Add GetSignatureAnnotation to unstarted runtime

Add support for Class.getSignatureAnnotation to the unstarted
runtime. Refactor dex file annotation code to support transactions.

Bug: 34956610
Test: m
Test: m test-art-host-gtest-unstarted_runtime_test
Test: Device boots
Change-Id: I9f4a93e05ad6999c46c3bb1dbabe48a1ad6225b2