[feat] add support for json query

[vi3k6i5]

Add support for Json Query: https://cloud.google.com/spanner/docs/json_functions

[peteryin21]

Hi @vi3k6i5, what's the status of this request?

[murabo]

Hi @vi3k6i5, what's the status of this request?

[chalmerlowe]

This issue was moved from the following repo as part of the monorepo migration: googleapis/python-spanner-django