Add graphs for more sar metrics

[m0dular]

Use Case

Currently the included system metrics dashboard only includes graphs for %cpu and %mem, but we collect more, e.g. system_cpu.iowait. Add or edit graphs to show any of these that may be useful.

[genebean]

If this is added, it should include a config option as many shops, such as ours, already collect such metrics and we don't want this module to conflict with existing code without the needed config options to remove the conflict. Having them default to on would be totally fine IMO though.

[m0dular]

@genebean Thanks for weighing in. I realized this ticket should be about including graphs for more of what we currently collect, so we'll make a new ticket for collection of more sar metrics in the metrics_collector module.