Update the Find-References feature to only find inheritance results that could lead to a specific member being used at runtime.

[CyrusNajmabadi]

Previously, 'Find References', which has both an programmatic API (FAR-API), and an end user facing feature (FAR-feature) would walk unilaterally through the inheritance hierarchy for a member with a particular. So, if you had:

class C { public virtual void Foo() {} }
class D1 : C { public override void Foo() { } }
class D2 : C { public override void Foo() { } }

Then doing a Find-References on D1.Foo, would find references to all three Foo methods shown there. This was non ideal if you consider this sort of case:

D2 d = new D2();
d.Foo();

Here, this call to Foo can never, and will never call into D1.Foo(). Any call through it will never reach D1's Foo method. Contrast this with:

C c = ...;
c.Foo();

Here, c.Foo() could call into D1.Foo if c is an instance of D1 at runtime.

The reason FAR-feature worked this way, is that it calls FAR-API to get the results. This FAR-API was designed for needs of consumers like Rename. In Rename, if you rename any of these three methods, then all have to be renamed as there is a coupling here between the members in terms of satisfying interface implementations. That coupling goes beyond what FAR-feature needs, but it caused the suboptimal behavior seen above.

This change introduces a new concept to FAR-API where the client can specify if they want this behavior or not. Existing clients (like rename, or 3rd parties) will get the same results as before. However, clients (like FAR-feature, highlight-refs, and CodeLens) can opt into new behavior where we only find references that could actually call into that member at runtime.

This also has added benefits for performance as things like codelens (and FAR-feature, and highlight-refs) wont' cascade to many symbols that aren't needed when computing these results.

[CyrusNajmabadi]

this is the meat of hte change. might be easier to read with whitespace changes off.

[sharwell]

💡 The SelectAsArray isn't helping here. It would be better to either use Select, or an extension that allows AddRange with a transformation argument.

[ghost]

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