Cloud instance name should allow leading numerics

[fantix]

1st1/test or fantix/1st1test should be accepted as valid instance names.

• Regexp: ^(\w(?:\w|-(?=\w))*)(?:/(\w(?:\w|-(?=\w))*))?$
• Total length should not be greater than 62 if / (inclusive) is present, so that the translated cloud domain label inst--org is no longer than 63 letters.
• Don't narrow the limit on local instance names

[zackelan]

this has an unofficial but legit-looking regex for org slug. the "no consecutive hyphens" and "can't start or end with a hyphen" requirements may not be relevant for our regex because we shouldn't ever see a Github user with that name...but it does mean that we can safely treat -- as an internal DNS name separator because it will never appear in a org name.

I think cloud & local instance names should have identical requirements unless there's a very good reason to make them separate. if I have a local instance and want to migrate it to be hosted in the cloud, it would be annoying friction to be required to make up a new instance name as well

[fantix]

I think cloud & local instance names should have identical requirements unless there's a very good reason to make them separate. if I have a local instance and want to migrate it to be hosted in the cloud, it would be annoying friction to be required to make up a new instance name as well

With the updates from the discussion, this is not valid any more because:

1. Local instance names may have underscores _ and we don't want to narrow down the existing limit
2. Cloud instance names must not have underscores

The best we can do now is to allow single dashes - in local instance names like the cloud names (and leave underscores be).