Session host bypass fix

[at88mph]

This PR addresses a diagnosis need to set a separate hostname to bypass some proxies, or potentially host user sessions (workload) on a different cluster or host.

Key Changes:

1. Hostname configuration from the SKAHA_SESSIONS_HOSTNAME environment variable.
2. Cleanup for static utility methods
3. Added unit tests

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 21.00%. Comparing base (25ddfed) to head (f622097).

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #784      +/-   ##
============================================
+ Coverage     20.60%   21.00%   +0.40%     
- Complexity      118      122       +4     
============================================
  Files            23       23              
  Lines          1980     1985       +5     
  Branches        270      268       -2     
============================================
+ Hits            408      417       +9     
+ Misses         1521     1519       -2     
+ Partials         51       49       -2     

Flag	Coverage Δ
skaha-unittests-coverage	21.00% <ø> (+0.40%)	⬆️

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