Add downstream mTLS support

[sgayangi]

Purpose

• Part of Add downstream mTLS support #1839
• Adds the adapter side changes to support downstream mTLS
• SDS configuration will be done in a separate PR

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (75f182a) 26.71% compared to head (98ca8f6) 26.54%.
Report is 5 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1857      +/-   ##
==========================================
- Coverage   26.71%   26.54%   -0.18%     
==========================================
  Files         248      124     -124     
  Lines       28789    14513   -14276     
  Branches     5132     2575    -2557     
==========================================
- Hits         7692     3852    -3840     
+ Misses      20849    10537   -10312     
+ Partials      248      124     -124     

Flag	Coverage Δ
adapter	24.60% <ø> (-0.27%)	⬇️
common-controller	4.62% <ø> (ø)
config-deployer-service	26.80% <ø> (-0.03%)	⬇️
idp-domain-service	80.18% <ø> (ø)

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