Proposal: Describe possible project structure and implications

Initial thoughts around scoping Kubernetes resources to projects and the associated implications.

Intended as a complement to #891, but with more detail on the implementation consequences of project scoping throughout the stack.

Would like to get general agreement on an outline to proceed against to support an initial prototype in next couple weeks.
Rephrase: When we come up with a constraint system, all project-imposed scheduling details will be expressed as constraints which the scheduler is expected to follow.