Create user worker runs

Refs https://redmine.teklia.com/issues/4471

An API user with verified email should be able to create worker runs tied to their account through a new endpoint CreateUserWorkerRun.

It must take as input:

• worker version id (required)
• model version (optional)
• configuration (optional)

A few checks are important:

• the worker version should not be tied to a git revision
  • and so the worker should not be tied to a git repo
• the worker must be executable by current user
• the model (if any) must be accessible with guest access

A local process tied to the current user account must be get or created.