Add ability to send logs via OpenTelemetry to collector

<!-- Please only use this template for submitting feature requests --> **Why is this needed**: We want Grafana application logs in our central log server. syslog support is there, OpenTelemetry tracing is also supported, but OpenTelemetry logging should be there as well. **What would you like to be added**: Send Grafana logs to any logging server that supports OpenTelemetry. **Who is this feature for?** Anyone wanting future-proof centralized logging.