[feat] Add support for dynamically setting the authorization header in the http logging handler

[JimPaine]

Enables the use of short lived tokens where http services use flows such as client credentials by allowing the authorization header to be set dynamically via a callable which is evaluated at the point the http request is made.

Closes #3622

[codecov]

Codecov Report

❌ Patch coverage is 16.66667% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.34%. Comparing base (a6b2619) to head (a1cf54c).

Files with missing lines	Patch %	Lines
reframe/core/logging.py	16.66%	5 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #3624      +/-   ##
===========================================
- Coverage    91.39%   91.34%   -0.05%     
===========================================
  Files           62       62              
  Lines        13520    13526       +6     
===========================================
- Hits         12357    12356       -1     
- Misses        1163     1170       +7     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.