Add Google and Microsoft OAuth authentication

[DianaAliabieva]

This PR implements authentication for Google and Microsoft. To get this running, the following environment variables need to be configured:

GOOGLE_OAUTH_CLIENT_ID

GOOGLE_OAUTH_CLIENT_SECRET

MICROSOFT_OAUTH_CLIENT_ID

MICROSOFT_OAUTH_CLIENT_SECRET

[codecov]

Codecov Report

❌ Patch coverage is 50.56180% with 44 lines in your changes missing coverage. Please review.
✅ Project coverage is 78.47%. Comparing base (e9775f2) to head (b44fcd2).
⚠️ Report is 57 commits behind head on main.

Files with missing lines	Patch %	Lines
pydatalab/src/pydatalab/routes/v0_1/auth.py	45.45%	42 Missing ⚠️
pydatalab/src/pydatalab/feature_flags.py	66.66%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1705      +/-   ##
==========================================
- Coverage   79.24%   78.47%   -0.77%     
==========================================
  Files          79       81       +2     
  Lines        6731     7127     +396     
==========================================
+ Hits         5334     5593     +259     
- Misses       1397     1534     +137     

Files with missing lines	Coverage Δ
pydatalab/src/pydatalab/config.py	80.53% <100.00%> (+0.67%)	⬆️
pydatalab/src/pydatalab/models/people.py	94.69% <100.00%> (+0.24%)	⬆️
pydatalab/src/pydatalab/feature_flags.py	76.00% <66.66%> (-0.82%)	⬇️
pydatalab/src/pydatalab/routes/v0_1/auth.py	59.55% <45.45%> (-3.83%)	⬇️

... and 18 files with indirect coverage changes

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