pub fn validate_ref_name(name: &str) -> Result<(), Error>Expand description
Is this a name a ref or tag can HAVE?
Deliberately separate from crate::namespace::validate_name: a
collection name becomes a directory, a ref name becomes a CLI argument, and
the failure modes do not overlap.
Every rule here refuses rather than sanitises. A name silently rewritten is a different pointer than the one the caller asked for, and they would find out from the wrong build artifact rather than from an error.