Add baggage header to RestTemplate

[adinauer]

📜 Description

Add baggage header to outgoing RestTemplate calls.

💡 Motivation and Context

To support Dynamic Sampling for outgoing requests using RestTemplate

See #2205

💚 How did you test it?

Unit Test

📝 Checklist

• I reviewed the submitted code
• I added tests to verify the changes
• I updated the docs if needed
• No breaking changes

🔮 Next steps

[codecov-commenter]

Codecov Report

Merging #2206 (b262c15) into main (7dd32c0) will decrease coverage by 0.01%.
The diff coverage is 0.00%.

@@             Coverage Diff              @@
##               main    #2206      +/-   ##
============================================
- Coverage     80.65%   80.63%   -0.02%     
  Complexity     3355     3355              
============================================
  Files           240      240              
  Lines         12324    12327       +3     
  Branches       1633     1634       +1     
============================================
  Hits           9940     9940              
- Misses         1778     1781       +3     
  Partials        606      606              

Impacted Files	Coverage Δ
...racing/SentrySpanClientHttpRequestInterceptor.java	0.00% <0.00%> (ø)

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[lbloder]

LGTM