Implement stats object that can store stats from each request about ztunnel

[stevenctl]

This may need a bit of investigation to nail down requirements. At a minimum:

Stats per identity (or pair of identities) for things such as:

Total connections

Failed connections

Active Connections

Many other things

See Envoy’s upstream cluster stats for some examples of what we want to track.

[jewertow]

As we've talked, I will do some research on this topic and will try to prototype something.

[SkyfireFrancisZ]

Jacek is prototyping the type of metrics to be collected.

Best to submit a PR with instrumentation and minimal metrics to kickstart the discussion.

[linsun]

The task requires more than stats obj, @jewertow would like to unassign him for now.

[stevenctl]

#244

[stevenctl]

Should we close this or continue to track work for inbound stats here?

[howardjohn]

I think we can use this to track future stats

[SkyfireFrancisZ]

will have PR out later today

[howardjohn]

Basic stats are implemented