layers:Save mem accesses in read/write maps

This commit stores memory accesses into separate read and write maps.
This provides a perf boost for checking potential memory access faults
by eliminating uneccessary checks when previous access maps that would
be checked are empty so we don't iterate over maps that have no
potential for any conflicts.

A couple of other changes to cleanup memory access checks:
1. Merge "Add*MemoryAccess()" and "ValidateMemoryAccesses()" functions
into a single "CreateAndValidate*MemoryAccess()" function. This creates
the local access struct and validates it, but it won't be recorded into
the CB until/unless validation passes.
2. Split Mem access violation reporting into a separate function that
can be shared by a couple of different cases that flag errors.

Author: tobine