Unified driver dmc batched

[PDoakORNL]

First installment of DMCBatched driver. Much the same pattern as the VMCBatched driver. Unit tests to basic instantiation. Does not appear to break existing production code. Debuggin in advanceWalkers.

[PDoakORNL]

This is a good place to stop this PR as the next step is refactoring the branch engine and walker controllers which will be quite involved.

[prckent]

Can you ("we") defer updating the branch engine and walker controllers or is this required to get DMC batched working and estimate a FOM + throughput vs system size?

[PDoakORNL]

Can't be completely avoided due to heavy use of MCWalkerConfiguration in those classes' API's. Often that whole mess is being passed to just get access to a few members in the inherited name space.

But I'm defering it as much as possible. My plan is a max speed refactor into new method functions that don't rely on DMCUpdate or MCWalkerConfiguration.

[prckent]

Is the default walker count handling consistent with the old DMC drivers?

[PDoakORNL]

Yes, but I think and A/B unit test is still in order.

[prckent]

In the interest of development velocity and real consequential deadlines this needs to get merged. If no one comments within the hour that they are looking at this I will merge the PR ahead of tonight's nightlies.

[prckent]

Walker count behavior to be checked in future.

[prckent]

(Mark reports no comments)