Use autoconfigured ClassLoader to load declarative config

[jack-berg]

Agent extensions aren't currently able to provide declarative configuration ComponentProvider SPI implementations because the agent requires a them to be loaded using a particular class loader.

This adds a new FileConfiguration#create overload which allows SpiHelper (which is based on a ClassLoader) to be specified, and updates AutoConfiguredOpenTelemetrySdkBuilder to call this new method.

[codecov]

Codecov Report

Attention: Patch coverage is 95.00000% with 2 lines in your changes missing coverage. Please review.

Project coverage is 90.06%. Comparing base (39b2411) to head (16a4e67).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...nfigure/AutoConfiguredOpenTelemetrySdkBuilder.java	90.90%	1 Missing ⚠️
...ension/incubator/fileconfig/FileConfiguration.java	92.30%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##               main    #6725   +/-   ##
=========================================
  Coverage     90.06%   90.06%           
- Complexity     6457     6463    +6     
=========================================
  Files           718      718           
  Lines         19511    19528   +17     
  Branches       1922     1923    +1     
=========================================
+ Hits          17572    17588   +16     
  Misses         1350     1350           
- Partials        589      590    +1     

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