Add JSON schema to the tags register

[garethsb]

Now that we have several entries in the tags register, it would be good to add a JSON schema that checks the syntax of the string values based on the tag name.

• BCP-002-01 urn:x-nmos:tag:grouphint/v1.0 array elements must be strings matching the template <group-name>:<role-in-group>[:<group-scope>].
• BCP-003-03 urn:x-nmos:tag:certprov array elements must match the template v<MAJOR>.<MINOR>
• VSF TR-09-2 urn:x-vsf:tag:tr-09-2:booking-list/v1.0 array elements must match the template <consumer-id>:<booking-id>:<element-id>[:<label>]
• etc.

All of these could be checked to some degree using a regex pattern in a JSON schema, which could be used in implementations and in the testing tool.

I suggest a schema, tags_register.json, that can be applied to the tags attribute of any IS-04 (and IS-09, etc.) resource.