feat: Add writer for Avro GenericRecord

[anthavio]

Add AvroStreamWriter to write Avro GenrericRecords

Pull request is WIP and following is TODO but I'd need bit of guidance how to tackle bits that require refactoring/integration with existing code

• Conversions code of JsonToProtoMessage can be shared with AvroToProtoConverter
• AvroStreamWriter is 99% same as JsonStreamWriter
• Tests are missing

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Fixes #2662☕️

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