feat(cli) Add gh auth and docker auth prechecks to subo create release

[javorszky]

While attempting to release version 0.3.2, I ran into two issues:

• for whatever reason I had a github token saved into my env which didn't have sufficient access rights to create a tag on subo, and
• the post release subo docker publish failed because I wasn't logged in to docker, and even if I was, my user has no access to the suborbital docker team, so I couldn't publish the image

In order to run the release successfully we should test both of these that we're logged in, AND have the correct access rights to complete a full release.