Support for bigquery json type

[quom]

(While submitting an issue briefly describe the problem you are facing or a new feature you would want to see added)

The tags column is stored as a JSON object so it is natural for this also to be stored as a JSON type in biqquery.

Currently the remote read functionality uses the JSON_EXTRACT function which operates on JSON formatted strings and not JSON columns leading to query errors on remote read.

It would be good to support the JSON value type as this gives more concise query expressions compared to using JSON_EXTRACT on strings.