Improvement: Add method support to GenericProxy

### What

Goal: `score::mw::com::impl::GenericProxy` currently only supports Event communication. Since now also Methods are available it shall be extended with `GenericProxyMethod` support.

### How

1. Introduce a `GenericProxyMethod`. It should be similar to `GenericProxyEvent`
2. Design/Decide, how the signature of GenericProxyMethod shall look like! I guess - opposed to our existing ProxyMethod template variants, it won't be a class template at all. The signature for call operator should look like this:
`score::Result> operator()(MethodInArgPtr>);`
There we need void-specializations for the pointers above ...

### Estimates for realization

Rough estimate: 2 weeks

### Category

- [x] Affects Detailed Design

### Requirements / Architecture

- [x] Requirements / Architecture are not affected by this change?