Add shotover metrics profiler

[rukai]

Add a new windsock profiler (--profilers shotover_metrics) that fetches metrics from shotovers prometheus web interface.

When I implemented sar based system metrics, I set it up to extract specific hardcoded metrics from the full pool of metrics collected by sar. This made sense there as:

• sar collects a lot of metrics and only some of them are relevant
• sar's naming was quite poor and we can give better names for each item
• we can define an appropriate Goal value for each metric.

However for prometheus metrics I opted to include all metrics as long as we know how to handle that type of metric.
My reasoning is:

• Metrics are very dyanamic, new metrics are added or removed just by adding or removing transforms, so we need to dyanamically adapt to that.
• All metrics are relevant - no need to filter some out
• The names are fine as is - no need to rename them

Unfortunately this does come at the cost of not being able to define goals for some types of metrics.

Running with --cloud doesnt work yet due to EC2 security groups, this will be complicated to resolve, so for now lets land as is because I dont need it to work in the cloud yet.

Running:

cargo windsock --profilers shotover_metrics "name=kafka shotover=message-parsed topology=cluster1|single"
cargo windsock --results-by-tags ""

we get: