Refactor modules to make imports easier

[MrCreosote]

Now it's always

from kbase.auth import <whatever>

...and puts everything else in an _auth package to protect from collisions if we want to put other modules in the kbase namespace

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (92b00f8) to head (2f2d27b).
⚠️ Report is 6 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main        #9   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            4         5    +1     
  Lines          269       253   -16     
=========================================
- Hits           269       253   -16     

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