versionutils: support more than 1 label variant and their strict order

[nfuden]

The default list can be overridden by any consumer if they so choose but it states when a format is better than alphanumeric. One consideration reviewers should take into account is whether it makes sense to use string prefix or to convert these things into a regex. As it is now rcblah1 will be treated like rc1 which may not be ideal but in general it makes the code cleaner. BOT NOTES: resolves https://github.com/solo-io/go-utils/issues/0000

[solo-changelog-bot[bot]]

Issues linked to changelog: https://github.com/solo-io/go-utils/issues/0000

[nfuden]

probably should have been in the validator