GORM implicitly sets 'created at', 'updated at' and 'deleted at' timestamps
to 'now' by calling a 'now function'. This is now implemented by Flamenco
directly, instead of relying on GORM.
Ref: #104305
Instead of returning an error when getting the sqlc queries object, just
panic. This'll make the calling code quite a bit simpler. The situation
in which it might error out is so rare that I've never seen it, and I
don't even know if it will ever be possible to happen with the SQLite
implementation we use now. Furthermore, once we get rid of GORM, it
should just always work anyway.
Ref: #104305
Convert most of the job blocklist queries from GORM to sqlc. The management
functions (add worker, remove worker, clear list, fetch list) have been
converted.
As it was decided that the name "tags" would be better for the clarity
of the feature, all files and code named "cluster" or "worker cluster"
have been removed and replaced with "tag" and "worker tag". This is only
a name change, no other features were touched.
This addresses part of #104204.
Reviewed-on: https://projects.blender.org/studio/flamenco/pulls/104223
As a note to anyone who already ran a pre-release version of Flamenco
and configured some worker clusters, with the help of an SQLite client
you can migrate the clusters to tags. First build Flamenco Manager and
start it, to create the new database schema. Then run these SQL queries
via an sqlite commandline client:
```sql
insert into worker_tags
(id, created_at, updated_at, uuid, name, description)
select id, created_at, updated_at, uuid, name, description
from worker_clusters;
insert into worker_tag_membership (worker_tag_id, worker_id)
select worker_cluster_id, worker_id from worker_cluster_membership;
```
