Add related names to django models

[johannaengland]

Closes #2418

Will squash the commits together after reviews

[codecov]

Codecov Report

Merging #2423 (1fd549f) into master (f4a6adc) will increase coverage by 0.06%.
The diff coverage is 39.10%.

@@            Coverage Diff             @@
##           master    #2423      +/-   ##
==========================================
+ Coverage   52.64%   52.70%   +0.06%     
==========================================
  Files         552      552              
  Lines       40167    40186      +19     
==========================================
+ Hits        21144    21180      +36     
+ Misses      19023    19006      -17     

Impacted Files	Coverage Δ
python/nav/eventengine/plugins/linkstate.py	26.27% <0.00%> (ø)
python/nav/ipdevpoll/neighbor.py	50.86% <ø> (ø)
python/nav/ipdevpoll/plugins/lldp.py	30.93% <0.00%> (ø)
python/nav/ipdevpoll/plugins/statports.py	35.63% <0.00%> (ø)
python/nav/ipdevpoll/shadows/__init__.py	42.64% <0.00%> (-0.03%)	⬇️
python/nav/ipdevpoll/shadows/netbox.py	59.25% <0.00%> (ø)
python/nav/models/arnold.py	91.20% <ø> (ø)
python/nav/models/event.py	79.73% <ø> (ø)
python/nav/models/images.py	77.08% <ø> (ø)
python/nav/models/msgmaint.py	79.54% <0.00%> (ø)
... and 54 more

---

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[github-actions]

Test results

     12 files       12 suites   12m 14s ⏱️
3 086 tests 2 990 ✔️   96 💤 0 ❌
8 733 runs  8 445 ✔️ 288 💤 0 ❌

Results for commit 1fd549f.

♻️ This comment has been updated with latest results.

[lunkwill42]

Wow. What a beast. Other than my multiple inline comments, I have two requests for the future:

1. Please break things like this into multiple PRs. It's a nightmare to review and keep track of changes underway.
2. Please do not force-push changes after a review. Adding more commits makes it easier to see what has changed since the last review - and everything can be squashed once approved.

[johannaengland]

The force push was because of a rebase onto master

[johannaengland]

Yes, much better, but there are still loads of comments from my last review that still have not been addressed.

Should be fixed now - Github tried to hide these comments from me 😄

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
0.0% Duplication

[johannaengland]

Due to the massive size of this PR I have split it up into several smaller ones.