R1:575c01373ee7

Extract repository command construction from Repositories

Summary:
Ref T4292. Ref T10366. Depends on D15751. Today, generating repository commands is purely a function of the repository, so they use protocols and credentials based on the repository configuration.

For example, a repository with an SSH "remote URI" always generate SSH "remote commands".

This needs to change in the future:

- After T10366, repositories won't necessarily just have one type of remote URI. They can only have one at a time…