refactor: move configuration loading logic out of the extension context

[ndr-brt]

What this PR changes/adds

Add new ConfigurationLoader component that takes care of configuration loading (as ExtensionLoader is doing for extensions).

Why it does that

refactor

Further notes

List other areas of code that have changed but are not necessarily linked to the main feature. This could be method
signature changes, package declarations, bugs that were encountered and were fixed inline, etc.

Linked Issue(s)

Closes #4158

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[codecov-commenter]

Codecov Report

Attention: Patch coverage is 93.54839% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 75.02%. Comparing base (7f20ba5) to head (3ac720a).
Report is 246 commits behind head on main.

Files	Patch %	Lines
...junit/extensions/DependencyInjectionExtension.java	0.00%	1 Missing ⚠️
.../junit/extensions/TestServiceExtensionContext.java	50.00%	1 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4162      +/-   ##
==========================================
+ Coverage   71.74%   75.02%   +3.27%     
==========================================
  Files         919     1007      +88     
  Lines       18457    20453    +1996     
  Branches     1037     1151     +114     
==========================================
+ Hits        13242    15344    +2102     
+ Misses       4756     4608     -148     
- Partials      459      501      +42     

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