Support removing moxi ports from bucket configs in the CLI (and deprecate the ability to create moxi ports)

As described in https://issues.couchbase.com/browse/MB-21226?focusedCommentId=263938&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-263938 but copied here for convenience.

1. Add CLI support to remove the moxi port from the bucket config (unless it already exists)
2. Deprecate the ability to create a bucket with a moxi port

The reason (1) is important is I want to be able to direct users to remove the moxi port from a bucket before they upgrade to Mad Hatter (when we will have removed moxi). I would like them to do this via the CLI and not the REST API.

Once this is done I'd like to add a UI warning instructing users to run this CLI command.