OTEL logs exporter parameters

{:ns     main
 :import #{aidbox
           aidbox.log
           config}

 open-telemetry-appender
 {:zen/tags   #{aidbox/service}
  :engine     aidbox.log/open-telemetry-appender
  :config     {:url "http://url-to-otel-collector/v1/logs"
               :headers {"X-custom-logs-header" "header value"}}

 box
 {:zen/tags #{aidbox/system}
  :config   config/zen-config
  :services {:otel-appender open-telemetry-appender}}}