Cascade between position record parameters and properties.

[CyrusNajmabadi]

Fixes #44559

[RikkiGibson]

Talking offline, we think it would be ideal for the compiler to expose public APIs which let the IDE do the right thing here for both source and metadata scenarios.

For example, if a record Rec is declared in a referenced assembly:

var rec = new Rec(param: 1); // find-all-refs on "param" here
_ = rec.param.M(); // should include 'param' in results

I'm going to take a stab at coming up with public API that would address the scenario and we can bring it to API review.

[davidwengier]

I think we'll still probably get complaints about this until the new API is available, but good to make at least some scenarios better in the meantime.

Does this also fix #50450? or even #44560 maybe?

[CyrusNajmabadi]

Does this also fix #50450? or even #44560 maybe?

Very likely. I'll check today!