Remove unnecessary const declarations across the native simulator codebase

[AniketDalvi]

As a part of public class interface a const setter doesn't make much sense, whatever the implementation details of other methods might be. If clients outside of the class need to use the setter (for example, tests), make it non-const for them and inside flush() do the assignment directly, without going through the setter.

Originally posted by @irinayat-MS in #291

[AniketDalvi]

The current native simulator codebase has some const declarations which results in some non-ideal design patterns including const setters. This issue is to rethink the logical\representational constness model of the data structures in the full-state simulator codebase.

[bettinaheim]

@swernli @dbwz8 Does this still make sense after Dave's refactoring?

[swernli]

I'll double check the code and see. It's definitely possible this was already addressed as part of Dave's latest work.

[bettinaheim]

@swernli Did you have a chance to take a quick look?

[swernli]

I did, and I think we don't need to leave this open. The work that originally prompted this issue was the wave function reordering, which Dave's is looking at refactoring now, but is not yet covered by the current outstanding PR (#361). Either the refactor will appropriately remove the consts that aren't logically correct, or it will rework the way the underlying data structures are modified in order to no longer need the setters and the existing code can remain const. But the issue of const setters is only present in the feature/simulator-enhancement branch that has Aniket's changes and is not actually present in master.

[swernli]

Simulator enhancements have been merged via #361 and this can be closed as it is no longer an issue.