Rename the session_id to group_id in kvstores table in the SQL store, to
better represent how the field is actually used.
Note that this is a breaking change, and would normally require a new
migration. But as the SQL store is not used in production, and only
enabled under the dev build flag, we can rename it without a new
migration, as there's no users of the SQL store in production.
In this commit we define the schema for the `actions` table along with
various queries we will need for interacting with the table. NOTE: we
will also add some of our own queries manually in commits to follow.
This commit also contains the sqlc.yaml file, the `make sqlc` command
and the script for generating sqlc code. This must be done in this
commit as the script only works if there are queries to generate from.
