Improving Metrics functionality

[derN3rd]

Hey there,

I'm currently trying to improve the metrics handling inside bullmq, especially two parts:

• being able to reset metrics
• have counters exported in the prometheus export

For the second part I already looked at the places where queue metrics (by state) and 'done' metrics (over time) are implemented. The second type of metrics should not be returned to the prometheus export, when metrics are disabled on the worker. But the prometheus export is on the queue.
I'm unsure if I should move the prometheus exporter into the worker (+ the needed util functions) or if a split solution with 2 independent export fns is the way to go.

As most of the existing functions (getMetrics,exportPrometheusMetrics etc), I doubt it would be a good call to implement this in the worker. So I would probably just add these metrics to the prometheus export without checking if the metrics are enabled (as we cannot access this from the queue-getters.ts)

Thanks in advance