Use reflection signature format in linker warnings

[sbomer]

Warnings which mention ref parameters should be formatted as Method(ref ArgType), not Method(Type&) as they currently are.

edit:
Let's use this issue to track the signature formatting discussed in #2461. So far we have been making a best-effort attempt to format signatures as they appear in C#, but It sounds like we would prefer for the linker warnings to use reflection notation for method signatures (and for the analyzer warnings to continue using C# signature formats.)

The reflection signature format is documented here and includes things like + for nested classes and square brackets for generic argument lists. We need to update the linker signature formatting to match this.

Capturing some other ideas from @marek-safar in #2461 (comment):

We could explore the option of customizing the output based on the compiler used to produce the assembly but I'm really not sure it's worth it and it still has shortcomings because there are many different compilers (e.g. iron python).

Another option would be the explicit --diagnostic csharp option but that for me would make sense if we enhanced C# compiler to produce more metadadata for illinker to easily map any metadata to C# syntax.

[jtschuster]

I don't think there's a reflection notation standard for the delimiters between type names and members, so we need to decide what we want to do for that. When we were following C# notation we used ., but that is already used in reflection notation as namespace delimiters only. To avoid making our own version of reflection notation we could use a format like member "Method" from type "TopNamespace.SubNameSpace.ContainingClass+NestedClass,MyAssembly". Otherwise, I believe IL uses Type::Method, which is not used in reflection notation, so I think that would make the most sense if we want a single path for members.