include proposal inputs in detail limits snapshot

[catkins-miso]

This was likely in prior iterations but the current schema is insufficient.

As a Ratings Provider
I want to know how the forecasted limits were determined
When a new limits snapshot is available
Without making multiple requests or corelating multiple resource representations
So that I can maintain operational awareness
And store evidence of compliance

As a Clearinghouse Provider
I want to archive the inputs used to determined the forecast limits
When a new limits snapshot is available
Without making multiple requests or corelating multiple resource representations
So that my long-term ratings archive is compliant

Snapshot use cases:

• Why wasn't my rating considered?
• Why was it considered by not respected?
• Non-repudiation--that is not my proposal.

[catkins-miso]

To be clear, there was already a "proposals-considered" in the detailed limits snapshot, but it only allowed for an identifier, and we took the proposal out as a first-class interop resource.