Implement consistent registry access for vcpkg command accessing ports

[Andréa Machizaud (theblackunknown)]

Description

This PR implements the behavior to consistently access a port and its versions for vcpkg command discussed in microsoft/vcpkg#18967

I consider this PR as a draft for now as I have only testing code changes on x-add-version and a new command format-port like it was suggested in the initial PR, and I am looking for feedbacks whether this is going into the right direction or not.

Although I have implement this wanted behavior as a separate struct CommandRegistryPaths containing vcpkg::Path, I feel like this would be more coherent if implemented directly as additional method on vcpkg::RegistryImplementation and vcpkg::RegistryEntry.
However as this is my first PR I lack context and experience with the code base to decide this is a good direction or not.

NOTE: This is only a partial implementation over the initial spec (e.g. read-only registry not implemented).

[Andréa Machizaud (theblackunknown)]

Robert Schumacher (@ras0219-msft) I take your emoji as a good sign, I'll keep this work going into the same direction !
Please share any feeedbacks whether this would be better to augment RegistryXXX classes instead.