bundlespec: rationalize the way we specify stream bundle version
Instead of having weird dedicated option for each version (v2, v3, etc) we
reuse the same "stream" parameters. This is consistent with the ability to
request a stream clone using "none-v2;stream=v2".
This changeset introduce no user visible change, this is pure internal cleaning.
# So GitLab doesn't think we're using tons of Perl
*.t -linguist-detectable