Handle exessively long help text for jobs.

[thebjorn]

Currently, long (especially multi-line) text in the help = property of Job classes mess up the job listings (manage.py runjob -l):

 bizautuser        - bizautuser_process_transfer_request     - daily          - Remind BAs to process pending transfer requests after 3 days,
                or notify finaut after 5 days. Also processes queued requests.
 finlib            - run_rules_action_pnr                    - quarter_hourly - Process results that are awaiting in QM-db
 gos               - sample                                  -                - My sample job.

this PR, by default, extracts an 80 character digest and uses the rich library to output the listing as a table:

Job List: 47 jobs
┏━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓
┃ appname           ┃ jobname                                 ┃ when           ┃ help                                                        ┃
┡━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┩
│ bizautuser        │ bizautuser_process_transfer_request     │ daily          │ Remind BAs to process pending transfer requests after 3     │
│                   │                                         │                │ days, or notify [...]                                       │
│ finlib            │ run_rules_action_pnr                    │ quarter_hourly │ Process results that are awaiting in QM-db                  │
│ gos               │ sample                                  │                │ My sample job.                                              │
└───────────────────┴─────────────────────────────────────────┴────────────────┴─────────────────────────────────────────────────────────────┘

or, if verbosity is set to 2 or higher (manage.py runjob -l -v2) outputs the entire help text, but formatted a little better:

Job List: 47 jobs
┏━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓
┃ appname           ┃ jobname                                 ┃ when           ┃ help                                                              ┃
┡━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┩
│ bizautrules       │ advisors_missing_updates                │ daily          │ Find all users who is missing goals according to their            │
│                   │                                         │                │ competencyplan where the deadline has passed for at least one of  │
│                   │                                         │                │ the goals. Add these users to a list that the BA's has access to  │
│                   │                                         │                │ where the BA can select them all to set them to 'hvilende' in the │
│                   │                                         │                │ authorization scheme where the goal is missing.                   │
│                   │                                         │                │                                                                   │
│                   │                                         │                │ For users who are not authorized, but has taken an exam but has   │
│                   │                                         │                │ not updated the competency of that exam, the rules needs to be    │
│                   │                                         │                │ rerun. The reason for this is that the rules will have to say     │
│                   │                                         │                │ that a module is not ok if the competency is not updated.         │
│ bizautrules       │ rerunrules                              │ daily          │ Re-run the rules in table ReRunRules that are due to run today.   │
└───────────────────┴─────────────────────────────────────────┴────────────────┴───────────────────────────────────────────────────────────────────┘

As an added feature, rich will render any console markup (https://rich.readthedocs.io/en/latest/markup.html) present in the help text.