Verify accuracy of `CURRENTLY_UNSUPPORTED` in `errors.yaml`

[tatu-at-datastax]

(note: from #2223 comment)

Looks like snippet CURRENTLY_UNSUPPORTED might be out of date (in errors.yaml):

  - name: CURRENTLY_UNSUPPORTED
    body: |-
      Currently API tables have limited support for: 
      
      - Cassandra `timeuuid`, `counter` types.
      - Tuple types.
      - Filtering and indexing on Cassandra collection types `list`, `map`, `set`.
      - Defining `maps`, `list`, or `set` columns using any key type other than `text` or `ascii`.
      
      Support for these features will be expanded in future releases.

we should sync that with code as necessary.

[tatu-at-datastax]

NOTE: snippet table is not optimal either -- this is for TABLE features -- might want to change as well.