Move the three current 'status variables' (stop, update and progress)
into a single 'WorkerStatus' struct. This is cleaner and will allow for
future workin this area without having to edit tens of 'startjob'
callbacks signatures all the time.
No functional change expected here.
Note: jobs' specific internal code has been modified as little as
possible, in many cases the job's own data still just store pointers to
these three values. Ideally in the future more refactor will be using a
single pointer to the shared `wmJobWorkerStatus` data instead.
Pull Request: https://projects.blender.org/blender/blender/pulls/113343
