OpenAPI emitter deduplicating parameters

[timotheeguerin]

As part of this PR(#1115) fixing various issue around parent and sourceProperty reference in projections the result was that parameters where always inlined when using KeysOf.

import "@cadl-lang/rest";

using Cadl.Http;
using Cadl.Rest.Resource;

op test(...KeysOf<Pet>): void;

model Pet {
  @key("petId")
  id: string;
}

One option is to call @friendlyName in KeysOf but just doing that result in the shared parameter to be called PetKeys if there is a single key.

[johanste]

We do want to trace the lineage of the KeysOf to the original model type that it came from. For Python, an example of code we (want to be able to emit) is:

class Cat:
    id: str
    name: str

class CatClient:
    def update_cat(self, cat: str | Cat, *, name: str | None = None) -> Cat: ...

In other words, take either the key properties of a resource or an instance of the resource as the argument to the method.

[nguerrera]

I've put together a proposal in the form of a PR that implements it:

#1577

We can review the PR description and small diff in the design meeting.

[nguerrera]

This was approved.

[markcowl]

closing in favor of the PR