fix: delete unused OIDC helpers / clean front

[SaboniAmine]

Description

Due to recent changes, the /users/{user_id} endpoint isn't needed anymore, the /auth/check endpoint is able to give back enough user information to manage authorization rules.
Also, some various helpers weren't needed anymore both in back & front end.
Also upgraded ESlint & added lint / format commands to package.json

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.70%. Comparing base (4afa249) to head (840a9b7).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1289   +/-   ##
=======================================
  Coverage   89.70%   89.70%           
=======================================
  Files          48       48           
  Lines        4778     4778           
=======================================
  Hits         4286     4286           
  Misses        492      492           

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[inimaz]

Some comments, other than that looks good, thanks @SaboniAmine!