Commit adds the following changes:
* Adds support of OpenTelemetry logs for Victoria Logs with protobuf encoded messages
* json encoding is not supported for the following reasons:
- It brings a lot of fragile code, which works inefficiently.
- json encoding is impossible to use with language SDK.
* splits metrics and logs structures at lib/protoparser/opentelemetry/pb package.
* adds docs with examples for opentelemetry logs.
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Related issue: https://github.com/VictoriaMetrics/VictoriaMetrics/issues/4839
Co-authored-by: AndrewChubatiuk <andrew.chubatiuk@gmail.com>
Co-authored-by: f41gh7 <nik@victoriametrics.com>
