FAR on Create method of a collection builder doesn't find all the usages

[jcouv]

Repro:

1. create a project with the code below
2. invoke FindAllReferences on the Create method
3. the result only shows one reference (in the [CollectionBuilder(...)] attribute) but should also list the usage in C c = [true, false];

using System;
using System.Collections;
using System.Collections.Generic;
using System.Runtime.CompilerServices;

[CollectionBuilder(typeof(Builder), nameof(Builder.Create))]
class C : IEnumerable<bool>
{
    void M()
    {
        C c = [true, false];
    }

    IEnumerator<bool> IEnumerable<bool>.GetEnumerator() => throw null!;
    IEnumerator IEnumerable.GetEnumerator() => throw null!;
}
internal class Builder
{
    public static C Create(ReadOnlySpan<bool> source)
    {
        return new C();
    }
}

Relates to test plan #66418

For context, here's how a similar issue was fixed previously (FAR on GetAwaiter methods involved in await): #28230

[CyrusNajmabadi]

Unlikely to support this. It's a niche case. We don't expect users to be typing these or doing FAR on these. They'll just get these handful of methods when they upgrade to a recent version of S.C.I.dll

[CyrusNajmabadi]

Would take a small targeted fix here.

[CyrusNajmabadi]

This is gated on having an actual compiler api. AFAICT< there is no way to query the compiler to ask what collection factory method the compiler used to construct a collection-expr. @jcouv to confirm.