ART: Find and cache indices for method names

Cache the range of string indices starting with '<,' especially the
well-defined "<clinit>" and "<init>," to optimize the constructor-flags
check.

Saves about .2% of instructions.

Bug: 78568168
Test: m test-art-host
Change-Id: I9ed26bb0382a169d945bcec4067c0166c200e227
3 files changed