Port the SQL Plug-in Lab Example to Temporal packages

The lab example is located at https://github.com/longquanzheng/cadence-extensions for SQLite. It would be nice to see a corresponding one for temporal, as it is mentioned in https://github.com/temporalio/temporal/blob/master/docs/persistence.md#for-sql-database

Thanks for consideration after your code stabilization phase.

This is an awesome idea. We will absolutely do this at some point.