Make `jobq [submit|stop|list|logs]` aware of project concept

Goals:

- Default is to operate on a single project
- `list` can also support `--all-projects/-A` to list from all projects the user can see

Additional tasks:

- Migrate existing commands to `jobq job` subcommand to prevent name clashes

Implementation considerations:

- Jobs are conceptually a subresource of projects, so it is probably sensible to make `/projects//jobs` the main API to interact with jobs (at least for submitting new ones). TODO: Examine what the [Zalando RESTful API guide](https://opensource.zalando.com/restful-api-guidelines/) has to say on this.