verifier: Partially refactor array access verification.

Verify `aget*` and `aput*` in one template function
`VerifyArrayAccess()` similar to `VerifyISFieldAccess()`.
Deduplicate some code and add FIXME comments for things
that we fail to verify or verify too strictly while
perfectly preserving old behavior, with the exception of
some failure messages now containing the full opcode.

Test: testrunner.py -b --host-gtest --host --optimizing
Flag: EXEMPT PURE_REFACTOR
Change-Id: I72388cf75b77e64a34093274649559ff8295ad94