[Proposal]: Type inference using method group natural type

# Type inference using method group natural type

* Specification: https://github.com/dotnet/csharplang/pull/10239
* Discussion: https://github.com/dotnet/csharplang/discussions/9006

## Summary
[summary]: #summary

It allows the natural type of a method group to contribute to method type inference, so scenarios like the following can work:

```
Test(IsEven); // Error CS0411 The type arguments for method 'Program.Test(Func)' cannot be inferred from the usage. Try specifying the type arguments explicitly.

partial class Program
{
public static bool IsEven(int x) => x % 2 == 0;
public static void Test(Func predicate) { }
}
```

## Design meetings

- https://github.com/dotnet/csharplang/blob/main/meetings/2024/LDM-2024-09-04.md#type-inference-using-method-group-natural-type