Add prometheus exporter

[dgmorales]

This PR instruments Keess code exporting metrics meant to be collected by Prometheus.

See metrics.go file for a description of the metrics being added here.

TODO (keep on draft while not complete):

• Instrument orphan service handling
• Count errors everywhere
• Instrument ConfigMap orphan handling
• Instrument Secret orphan handling
• Track remote client state (keess_remote_up metrics)
• Track resource management count (keess_resources_managed_total)

How this was tested

# Bring up the local clusters with Keess installed
# (or just `make install-keess` if cluster are already up)
make setup-local-clusters-with-keess

# Port forward into http service on the destination cluster (orphan metrics will show on the destination)
KUBECONFIG=localTestKubeconfig kubectl --context kind-destination-cluster -n keess port-forward services/keess 8080:8080

# Check the metrics (should be zeroed)
curl localhost:8080/metrics |grep keess

# Run our e2e test suite
make tests-e2e

# Check metrics again (should see increased numbers)

[Copilot]

Pull Request Overview

This PR adds Prometheus metrics instrumentation to Keess, enabling monitoring and observability of the operator's performance and health. The implementation includes metrics for error tracking, orphan resource detection/removal, and resource management counts.

Key changes:

• Created comprehensive metrics package with Prometheus counters and gauges for various operational aspects
• Instrumented service orphan handling with detection and removal metrics
• Added HTTP endpoint for metrics exposure and updated service configuration for Prometheus scraping

Reviewed Changes

Copilot reviewed 7 out of 8 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
pkg/keess/metrics/metrics.go	New metrics package defining Prometheus counters and gauges for errors, orphans, and remote cluster status
pkg/keess/service/service_deletion.go	Instrumented orphan service handling with metrics tracking
cmd/run.go	Added metrics registration and HTTP endpoint for Prometheus scraping
cmd/version.go	Version bump and variable export for metrics logging
chart/templates/service.yaml	New Kubernetes service template with Prometheus scraping annotations
chart/values.yaml	Added service configuration options for Prometheus integration
go.mod	Added Prometheus client library dependency

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[github-actions]

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