🎨 #600 - changed the error on 403 without session

[Xaohs]

closes #600

• Added a backend middleware to return a code on the session expiry edge case
• Added two E2E tests
  • One tests for the issue itself
  • Other one tests our authentication implementation directly (and changed the CSRF test to not hit this edge case anymore)
• Updated frontend to add a link to the modal when the session_expired code is provided as a response error

[Xaohs]

@svenvandescheur if needed, we can add Silvia as a reviewer aswell

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 89.28571% with 3 lines in your changes missing coverage. Please review.

Project coverage is 86.81%. Comparing base (90849eb) to head (1732718).

Files with missing lines	Patch %	Lines
frontend/src/hooks/useAlertOnError.ts	72.72%	3 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #612   +/-   ##
=======================================
  Coverage   86.81%   86.81%           
=======================================
  Files         205      205           
  Lines        5968     5991   +23     
  Branches      619      621    +2     
=======================================
+ Hits         5181     5201   +20     
- Misses        787      790    +3     

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[svenvandescheur]

Some small remarks, looks good otherwise.

[svenvandescheur]

We can make this 0/1 no?

[svenvandescheur]

This only works for the "session_expired" code, I think we should just filter out any record with the key "code", also please add some documentation on why this is and update the test file with a testcase for it :)