refactor: removed old method for authentication

[Lucino772]

Description

This PR removes the old method of authenticating with Mojang services. The yggdrasil method was replaced by Microsoft OAuth2 flow.

This PR also updates the documentation regarding the authentication.
This PR also adds new test for the MojangAuthenticationApp.

Type of change

• ⚠️ Breaking change (fix or feature that would cause existing functionality to not work as expected)
• 📃 Documentation (Documentation only changes)
• 🧪 Tests (Added missing tests)

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: +4.68 🎉

Comparison is base (cff160a) 74.33% compared to head (52e1e20) 79.02%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #69      +/-   ##
==========================================
+ Coverage   74.33%   79.02%   +4.68%     
==========================================
  Files          27       25       -2     
  Lines         908      820      -88     
  Branches       83       79       -4     
==========================================
- Hits          675      648      -27     
+ Misses        209      148      -61     
  Partials       24       24              

Impacted Files	Coverage Δ
mojang/api/urls.py	100.00% <ø> (ø)
mojang/api/auth/microsoft.py	100.00% <100.00%> (ø)
mojang/api/auth/models.py	79.38% <100.00%> (+11.66%)	⬆️
mojang/api/structures.py	100.00% <100.00%> (ø)

... and 1 file with indirect coverage changes

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