Query workbench schema sidebar broken when any bucket names contain '.' character

This is a regression between 7.0.3 and 7.1 reported by a user on the Couchbase Forums:

https://forums.couchbase.com/t/bucket-exploration-issues-after-upgrading-to-couchbase-7-1-0/33675

When the cluster has a bucket name containing the "." character, there is an exception in the code while processing the bucket permissions, and the schema sidebar appears blank.

The fix for this is relatively simple, and ready to go.