[Feature]: Expose configured bandwidth in perfdata

[LucaMH]

Describe the feature request

Currently, the value set via --bandwidth is not written to the perfdata.

This makes it a bit more annoying to use in third-party tools like Grafana, because the configured bandwidth value is not available there. There is a workaround by showing the percentage value in Grafana with scale(), but that feels a bit unflexible and puts the logic into the dashboard instead of the check output.

It would be nice if the bandwidth value from --bandwidth could also be added to the perfdata.

[martialblog]

@RincewindsHat Can you have a look at this?

[RincewindsHat]

yes