[hot reload] Mono needs to be more lax about CustomAttribute updates

[lambdageek]

The runtime accepts updates to a CustomAttribute row, as long as the parent and the "type" (really ctor) are "the same".

But the check for whether the ctor is "the same" is too strict - it expects token equality. That works for MethodDef tokens, but not for MemberRef tokens, because Roslyn emits fresh MemberRef (and TypeRef and AssemblyRef) rows into the delta.
So the token for the new ctor is not literally the same as the token for the old ctor.

We should trust that Roslyn won't send us anything unexpected - which it does not because changing the ctor or its argument data requires the ChangeCustomAttributes capability, which mono doesn't provide).

This particularly affects this-capturing lambdas.

Something like this:

  string field;
  void Method() {
    Action f = () => field += ".";
    f();
  }

Generates

   private string field;

    public void Method() { new Action(<Method>b__1_0)(); }

    [CompilerGenerated] // <------  this is a MemberRef
    private void <Method>b__1_0() { field += "."; }

[lambdageek]

Happens in Razor pages with a @bind because that generates a this-capturing lambda dotnet/aspnetcore#34446