ART: Add field offset caching

Add caching to reduce the computational complexity of deriving
field indices. Currently cache the number of interface fields.
In the future, we may also consider the superclass count to
accelerate class visiting.

Bug: 31385354
Test: m test-art-host
Test: m test-art-host-run-test-906-iterate-heap
Test: m test-art-host-run-test-913-heaps
Change-Id: I19da243d1678f9a4a047d849193fb8bac01ed53c