Identify which use cases are relevant to RADPS

[brendanpthomas]

• Tie use cases back to requirements
• Identify where context functionality may be handled by workflow manager or other solution
• Document has been created, and reviewed by Jan-Willem, Amanada, Eric, Mark Whitehead.

As Amanda and Eric, I want to know which context use cases will need to be covered by the RADPS implementation, so that we can create a RADPS pipeline that works

Estimated time: ~2 weeks (concurrent with #12)