Investigate what metrics can be surfaced from the gateway & other components, and visualised in Kiali

[david-martin]

Goal

Explore what metrics from the Istio Gateway can be enabled and visualised in Kiali.
The outcome of this may be issues for documentation in form of guides, and/or suggestions for new metrics in the MCP Gateway components (which can feed into #161).
This is very much an investigation and exploration issue.

Suggested approach

Set up the MCP Gateway in a cluster that can be easily shared with the Kiali team.
Taking the upstream guides at https://kiali.io/docs/, and install/configure Kiali and gateway metrics.
For setting up a Gateway, there's a flow in Kiali to create Gateway API resources. We should see if this works for setting up the MCP Gateway as well.
Let's work with the kiali team in the shared cluster to progress this investigation.

(Note there is an internal jira issue where we can engage the team as well with questions https://issues.redhat.com/browse/OSSM-12190)