Implement process context sharing OTEP-4719

[jhalliday]

OTEP-4719: Introduce a standard mechanism for OpenTelemetry SDKs to publish resource attributes for access by out-of-process readers such as the OpenTelemetry eBPF Profiler.
Elements of this implementation uses panama FFM (stable in Java 22+) to access native methods. It is not proposed to support process context on JDK releases earlier than 25.

[jhalliday]

@ivoanjo If you have time I'd appreciate you looking this over from the perspective of compliance to the spec. It's largely from your demo code so hopefully it's not too far off.

@jack-berg Thoughts on package structure, Java 25+ use, dependencies? It's pulling in existing protobuf support from the exporters rather than reinventing it.

I've not got gradle doing quite the right thing yet - it builds all the tests, but doesn't recognize the Java 25 ones as parts of the test set, so doesn't actually run them :-( Other than that, it's good enough as a starting point for discussions.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.64%. Comparing base (7aea89f) to head (fb85460).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #8718      +/-   ##
============================================
- Coverage     91.65%   91.64%   -0.01%     
+ Complexity    10352    10351       -1     
============================================
  Files          1003     1003              
  Lines         27210    27211       +1     
  Branches       3199     3199              
============================================
- Hits          24939    24938       -1     
  Misses         1566     1566              
- Partials        705      707       +2     

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