Add dynatrace example app

[lojzatran]

I added an example app to show how to use with this monitoring module: https://github.com/commercetools/commercetools-sdk-java-v2/pull/622

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 3.60360% with 107 lines in your changes are missing coverage. Please review.

Project coverage is 10.62%. Comparing base (29dd4b3) to head (71c5b3b). Report is 7 commits behind head on main.

Files	Patch %	Lines
...itoring/dynatrace/DynatraceResponseSerializer.java	0.00%	61 Missing :warning:
...toring/dynatrace/DynatraceTelemetryMiddleware.java	0.00%	45 Missing :warning:
...mercetools/monitoring/dynatrace/DynatraceInfo.java	0.00%	1 Missing :warning:

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #623      +/-   ##
============================================
+ Coverage     10.60%   10.62%   +0.02%     
- Complexity     1842     1850       +8     
============================================
  Files          6220     6225       +5     
  Lines         59405    59539     +134     
  Branches        265      271       +6     
============================================
+ Hits           6299     6326      +27     
- Misses        52941    53048     +107     
  Partials        165      165              

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[lojzatran]

We decided not to add dynatrace module for now.

Reason: it would add too much overhead as it uses HTTP to create new metrics. This would significantly slow down every request to commercetools. The other way for now for dynatrace is to use opentelemetry.