This feature is used by the coder agent to exchange a new token. By
protecting the SessionToken via mutex we ensure there are no data races
when accessing it.
* feat: Add bufferring to provisioner job logs
This should improve overall build performance, and especially under load.
It removes the old `id` column on the `provisioner_job_logs` table
and replaces it with an auto-incrementing big integer to preserve order.
Funny enough, we never had to care about order before because inserts
would at minimum be 1ms different. Now they aren't, so the order needs
to be preserved.
* Fix log bufferring
* Fix frontend log streaming
* Fix JS test
