ART: Additional Atomic methods

A few additional methods on the Atomic class to support the
interpreter VarHandles implementation.

Minor renaming of Atomic::FetchAnd{Or,And}.* to
Atomic::FetchAndBitwise{Or,And}.*.

Minor updates for consistency in the choice of argument names and doc
comments.

Bug: 65872996
Test: art/test.py --host -j32
Change-Id: Iae35286935fbb270478082fed2fe74abb7b68c57