OpenTelemetry

[rudimk]

Apart from Prometheus metrics, the exporter should have the ability to export metrics in OpenTelemetry's native format. The aim here is to rework the exporter where both formats are first-class citizens, with the user opting for one format.

Initial thoughts

1. Adding a command-line flag which allows users to switch between Prometheus and OpenTelemetry.
2. Maintaining the same metric names. This becomes useful if someone is moving between Prometheus and OTEL, allowing them to reuse telemetry queries and dashboards with minimal changes.