Powderhouse subsystems and directives

[KathleenDollard]

This addresses some of the issues raised in #2342 regarding directives (not response files environment variables(..

Remains in draft because:

• There are more changes to the Tokenizer than I expected to evaluate directives separately - these changes extended to several files
• I put some data onto the CLI Configuration, because I didn't know where to put it. When we determine how to carry information, we need to plan a way to tuck it away, probably similar to the SubSystem static class for subsystems.
• A major piece of information is where the Tokenizer should begin. There are two reasons for this - the exe name may or may not be included in the args array and we need to deal with this, and Initialize methods for subsystems may have handled some of the args. We are limiting that handling to the start of the args array.
• There are numerous naming and other issues to resolve, but I wanted to get the basics out for folks to look at before I am mostly busy next week.

[KathleenDollard]

This issue has files changed that I did not expect. I need to review this with Jean or Mikayla, regardless of content, and I know it makes it hard to review. So, unless you are in a patient mood, you can wait for a cleaner PR.

I did not deliberately delete most of the code marked as deleted.

[KalleOlaviNiemitalo]

The changes might be easier to understand if you updated the API compatibility test files too.

[KathleenDollard]

@KalleOlaviNiemitalo

The changes might be easier to understand if you updated the API compatibility test files too.

TBH, we are still getting everything to work with the split approach and have not given much thought to the API yet. We will do that a bit later.

I think the new subsystem approach will take some docs beyond API, and we're working on some design docs.