Add improved checks and behavior for memory with invalid values

[mkorbel1]

Description & Motivation

There were some concerns (e.g. intel/rohd#634) that things like the RegisterFile could have improper, overly optimistic behavior when invalid values were present on the write ports.

This PR:

• Adds more tests on all kinds of Memorys including RegisterFile and MemoryModel
• Adjusts pessimism on the MemoryModel
• Improves printing on invalid writes to the MemoryModel default behavior to prefer the Test.intance.logger, if available, instead of print.

Related Issue(s)

intel/rohd#634 (unable to reproduce)

Testing

Added more tests

Backwards-compatibility

Is this a breaking change that will not be backwards-compatible? If yes, how so?

No, though MemoryModel is now slightly less pessimistic

Documentation

Does the change require any updates to documentation? If so, where? Are they included?

No