Features
- Python den levels page ([1702](https://github.com/ocadotechnology/rapid-router/pull/1702),
[`701a36b`](https://github.com/ocadotechnology/rapid-router/commit/701a36b15a478bc87b8c2d3c3b13ba297d8f6270))
* begin work on levels page
* continue work on levels page
* make UI changes, revert URL changes
* more work on levels page
* add variable to track page path
* make levels page buttons conditional
* fix migrations
* debug with small changes
* update url ending
* reset unneeded changes
* debug test
* test the test
* fix typo
* test out something new
* undo previous changes
* test change to test settings
* add level urls
* make small updates
* fix conflicting migrations
* continue work on levels page and python den general setup
* fix types
* clean up tests, add episode urls to python den
* make some more episode url changes
* Optimise migrations
* Fix URLs and everything related to that
* Install portal branch
* Final fixes for URLs and tests
* Add redirection popup
* Final resource amendments
* Install latest portal
* Final optimisations
* Increase link fields lengths
* Black
* change redirect behavior for level-less episodes
* run black, write test, fix test
* fix test
* fix test syntax
* remove function call
* attempt fix syntax
* check for visibility instead
* try to fix test
* add test to test
* go straight to path
* fix path
* import reverse
* define and use new function
* update check slightly
* try checking different attribute
* fix playthrough test
* add specific redirecting check
* run black
* fix some resource links
* update levels used in locked levels test
* fix next level button
* address PR feedback
* rename level
* change strange descriptions, fix misplaced episode
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Co-authored-by: faucomte97 <f.aucomtehotmail.co.uk>