submodule-config: add repository argument to submodule_from_{name, path}

submodule-config: add repository argument to submodule_from_{name, path}

This enables submodule_from_{name, path} to handle arbitrary repositories.
All callers just pass in the_repository, a later patch will pass in other
repos.

While at it remove the extern key word from the declarations.

Reviewed-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Stefan Beller <sbeller@google.com>
Reviewed-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>