Consolidate curtailment calculations

[jaredthomas68]

Consolidate curtailment calculations

Currently, curtailment is calculated in many locations and this creates a lot of unnecessary code that is untested and difficult to read. I believe that most instances, if not all, should be using the same function.

Proposed solution

We could reduce excess code by creating a single curtailment function that all cases of curtailment calculations call on.

Alternatives considered

Keep it as is.

Additional context

When addressing greenheart we may need to curtail products besides electricity (hydrogen, ammonia, etc). So the curtailment would ideally be written generally to work in all use cases.