[exporterhelper] Introduce batching functionality

[dmitryax]

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This change introduces new experimental batching functionality to the exporter helper. The batch sender is fully concurrent and synchronous. It's set after the queue sender, which, if enabled, introduces the asynchronous behavior and ensures no data loss with the permanent queue.

Follow-up TODO list:

• Handle partial errors
• A missing part compared to the batch processor is the ability to shard the batches by context value.

Updates https://github.com/open-telemetry/opentelemetry-collector/issues/8122

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 93.18182% with 12 lines in your changes are missing coverage. Please review.

Project coverage is 90.95%. Comparing base (2fe7ed8) to head (8c83fd7).

Files	Patch %	Lines
exporter/exporterhelper/batch_sender.go	95.16%	4 Missing and 2 partials :warning:
exporter/exporterhelper/common.go	79.31%	4 Missing and 2 partials :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8685      +/-   ##
==========================================
+ Coverage   90.92%   90.95%   +0.02%     
==========================================
  Files         348      350       +2     
  Lines       18401    18576     +175     
==========================================
+ Hits        16732    16895     +163     
- Misses       1346     1354       +8     
- Partials      323      327       +4     

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[github-actions[bot]]

This PR was marked stale due to lack of activity. It will be closed in 14 days.