Add a "who are you" message

[tacaswell]

This allows plans to ask who is running them and make decisions accordingly.

ex, adaptive plans can use a less-hokey method than checking for None on every return.

This will be come more relevant an @awalter-bnl builds out the time estimator if we grow other simulator.

[danielballan]

What's the protocol for the expected response? Maybe we should separate out beyond "RE or not" into specific functionality:

• Are you allowed to move/trigger hardware?
• Are you allowed to read hardware?

The request itself should probably also communicate information, like "I am affirmatively adaptive," that the processor may do something with.