Collect count of VirtualServer, VirtualServerRoute and TransportServer resources

[shaun-nx]

Proposed changes

This change updates the base telemetry job to collect a count of VirtualServer and TransportServer resources that are observed by the Ingress Controller.

Closes #4902 and #4903

Testing

Test cases in collector.go cover scenarios where:

1. Resources in a watched namespace is counted
2. Resources not in a watched namespace is not counted
3. Resources deployed across multiple namespaces are counted if those namespaces are watched

Additional changes

Renamed telemetry.go to collector.go
Moved code related to the DiscardExporter out of collector.go and into exporter.go

Note: Tests in collector_test.go cover calls to the Export function in exporter.go

Checklist

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

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