Feat: Auto-create an association when an asso account is created

[TeddyRoncin]

• Route POST /auth/signup/cas creates an asso if the user provided is an asso user

[codecov]

Codecov Report

❌ Patch coverage is 95.45455% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 81.73%. Comparing base (66cfed5) to head (c31e373).
⚠️ Report is 3 commits behind head on dev.

Files with missing lines	Patch %	Lines
src/auth/auth.service.ts	95.23%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              dev      #67      +/-   ##
==========================================
+ Coverage   81.69%   81.73%   +0.04%     
==========================================
  Files         126      126              
  Lines        2141     2152      +11     
  Branches      421      410      -11     
==========================================
+ Hits         1749     1759      +10     
- Misses        356      388      +32     
+ Partials       36        5      -31     

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