Dyn type erasure without macros

[danakj]

The current trait type erasure requires virtual and forwarding explicitly to the methods of the trait along with macros to help opt a type implementing a trait into erasure.

https://cpp-rendering.io/c-type-erasure-without-macros/ suggests a way to get rid of the macros here.

[ONKARBH]

@danakj Would you like to assign me this issue? I will try to resolve all the problems.

[danakj]

I admit this is quite exploratory and underspecified at the moment. Maybe you could send a more detailed design proposal here?