Vitess VTAdmin users that can create shards can deny access to other functions

Vitess is a database clustering system for horizontal scaling of MySQL through generalized sharding. Prior to version 16.0.2, users can either intentionally or inadvertently create a shard containing `/` characters from VTAdmin such that from that point on, anyone who tries to create a new shard from VTAdmin will receive an error. Attempting to view the keyspace(s) will also no longer work. Creating a shard using `vtctldclient` does not have the same problem because the CLI validates the input correctly. Version 16.0.2, corresponding to version 0.16.2 of the `go` module, contains a patch for this issue. Some workarounds are available. Always use `vtctldclient` to create shards, instead of using VTAdmin; disable creating shards from VTAdmin using RBAC; and/or delete the topology record for the offending shard using the client for your topology server.