Introduce an "event bus"-like system. It's more like a fan-out
broadcaster for certain events. Instead of directly sending events to
SocketIO, they are now sent to the broker, which in turn sends it to any
registered "forwarder". Currently there is ony one forwarder, for
SocketIO.
This opens the door for a proper MQTT client that sends the same events
to an MQTT server.
Change the package base name of the Go code, from
`git.blender.org/flamenco` to `projects.blender.org/studio/flamenco`.
The old location, `git.blender.org`, has no longer been use since the
[migration to Gitea][1]. The new package names now reflect the actual
location where Flamenco is hosted.
[1]: https://code.blender.org/2023/02/new-blender-development-infrastructure/
Be more selective in what's saved to the database to speed some things up.
Most importantly, this avoids saving the entire job when a task status is
updated or a task is assigned.
Requeueing the tasks of a specific worker is now done in the
`TaskStateMachine`, such that it can be called from other services as
well in future commits.
This also makes the `LogStorage` service a dependency of the
`TaskStateMachine`, as it needs to write "this task was requeued" kind
of messages to the task logs.
