Allow a user to generate operators when generating .Equals

[CyrusNajmabadi]

No description provided.

[CyrusNajmabadi]

Feature looks like

And generates code like:

[CyrusNajmabadi]

Tagging @dotnet/roslyn-ide

Note: this is a followup PR to #17975. When that PR goes through, this PR will becomea lot smaller.

[Pilchie]

Not a full review, but when generating operator == need to check order1 for null if it's a reference type.

[Pilchie]

(or call the static object.Equals() though that add a lot of indirection (and boxing in value type cases)

[CyrusNajmabadi]

Not a full review, but when generating operator == need to check order1 for null if it's a reference type.

We do, if the type is a reference type. We don't when it's a value type :)

[CyrusNajmabadi]

In the reference case we call EqualityComparer<T>.Default.Equals(...), thus getting null checks, without any boxing or typechecks.

[CyrusNajmabadi]

Preemptively merging in. Let me know if there's anything you want me to change.