add option to provide headers to send as client

[aviramha]

Closes #1521

[codecov]

Codecov Report

Attention: Patch coverage is 50.00000% with 2 lines in your changes missing coverage. Please review.

Project coverage is 75.1%. Comparing base (41549bc) to head (d2f37da).

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #1523     +/-   ##
=======================================
- Coverage   75.1%   75.1%   -0.0%     
=======================================
  Files         78      78             
  Lines       6978    6980      +2     
=======================================
  Hits        5238    5238             
- Misses      1740    1742      +2     

Files	Coverage Δ
kube-client/src/client/config_ext.rs	53.0% <100.0%> (-0.6%)	⬇️
kube-client/src/config/mod.rs	45.0% <33.4%> (-0.4%)	⬇️

[clux]

Looks easy enough. One Q on clarity.

[clux]

LGTM. Thank you!