Clean up OAuth2 helper functions

[hmpf]

Depends on #894

This is step one in a multistep operation. See #862

[elfjes]

Why would there need to be an (optional) dependency on argus-htmx?

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 88.88889% with 1 line in your changes missing coverage. Please review.

Project coverage is 84.15%. Comparing base (140d45a) to head (0334b40).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
src/argus/auth/utils.py	88.88%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #898      +/-   ##
==========================================
- Coverage   84.18%   84.15%   -0.03%     
==========================================
  Files          90       90              
  Lines        4065     4065              
==========================================
- Hits         3422     3421       -1     
- Misses        643      644       +1     

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[hmpf]

Because the switcher imports things from argus_htmx.

I was thinking "pip install argus-server[htmx-frontend]".

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud