When the web interface is showing the Workers list, it should no longer
get updates about jobs. A new subscription type `allJobs` is added, and
the `uuid` field of the subscription is no longer mandatory.
A task's "activity" field is a string that describes the last-performed
operation on the task. In Flamenco 2, a Worker's "last activity" is the
timestamp at which it was last seen. Using the same term for different
things is confusing, and thus gets removed until the Worker's "last seen"
functionality is reimplemented.
Instead of having a per-setting boolean to control whether it's visible
or hidden, there are now four values:
- `visible`: always show.
- `submission`: only show in the UI of a job submitter (like a Blender
add-on).
- `web`: only show in the web interface for management, but not when
submitting the job.
- `hidden`: never show; only available to the job compiler script as
internal setting.
Rename `pkg/api/flamenco-manager.yaml` to `flamenco-openapi.yaml`, to
distinguish the OpenAPI definition file from the Flamenco Manager
configuration file of the same name (but in a different directory).
No functional changes.
