ART: Switch to name-based IMT hashing

Use a hash scheme based on the name. This keeps IMT slots stable
when dex tables change.

This incurs a severe performance penalty for computing the slot.
Measurements on host degraded from 30ns to an average of 85mus.
However, calls in compiled code will not incur this overhead.

Added a test comparing similar interfaces in similar dex files.

Bug: 31594153
Test: test-art-host
Change-Id: Ibb86679ee94bec561984ea25826e56b1a7964cd0