Add NodeCount to telemetry data

[jjngx]

Proposed changes

This PR adds the k8s node counting functionality for the telemetry data collector.

Log example after deployment to a local kind cluster with one node:

I0221 17:08:04.753632       1 collector.go:81] Collecting telemetry data
I0221 17:08:04.779743       1 collector.go:91] Exported telemetry data: {ProjectMeta:{Name: Version:} NICResourceCounts:{VirtualServers:0 VirtualServerRoutes:0 TransportServers:0} NodeCount:1}

Log example after deployment to a local kind cluster with three nodes:

I0221 17:15:05.111857       1 collector.go:81] Collecting telemetry data
I0221 17:15:05.130732       1 collector.go:91] Exported telemetry data: {ProjectMeta:{Name: Version:} NICResourceCounts:{VirtualServers:0 VirtualServerRoutes:0 TransportServers:0} NodeCount:3}

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• [X] I have read the CONTRIBUTING doc
• [X] I have added tests that prove my fix is effective or that my feature works
• [X] I have checked that all unit tests pass after adding my changes
• [ ] I have updated necessary documentation
• [X] I have rebased my branch onto main
• [X] I will ensure my PR is targeting the main branch and pulling from my branch from my own fork