Add variable to go-client request dashboard

[chiayi]

What type of PR is this?

Uncomment only one /kind <> line, press enter to put that in a new line, and remove leading whitespace from that line:

/kind breaking
/kind bug
/kind cleanup
/kind documentation

/kind feature

/kind hotfix

What this PR does / Why we need it:
This adds a variable to the go-client request dashboard so that you can drill down by controller, extensions, or all.

Which issue(s) this PR fixes:
Work on #2797

Special notes for your reviewer:
Here are some screenshots:

[google-oss-prow]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: chiayi, zmerlynn
Once this PR has been reviewed and has the lgtm label, please assign ericfortin for approval. For more information see the Kubernetes Code Review Process.

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[google-oss-prow]

New changes are detected. LGTM label has been removed.

[agones-bot]

Build Failed 😱

Build Id: 2e4180bd-09be-41de-af51-82c2689e6d59

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[agones-bot]

Build Succeeded 👏

Build Id: 925bb44c-8a5b-4d0c-90cb-2f1adc2bfdb6

The following development artifacts have been built, and will exist for the next 30 days:

• image: us-docker.pkg.dev/agones-images/ci/agones-controller:1.30.0-655e252-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-sdk:1.30.0-655e252-linux-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-ping:1.30.0-655e252-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-allocator:1.30.0-655e252-amd64
• Linux C++ SDK (build): agonessdk-1.30.0-655e252-amd64-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.30.0-655e252-amd64.zip

A preview of the website (the last 30 builds are retained):

• https://655e252-dot-preview-dot-agones-images.appspot.com/

To install this version:

• git fetch https://github.com/googleforgames/agones.git pull/2998/head:pr_2998 && git checkout pr_2998
• helm install agones ./install/helm/agones --namespace agones-system --agones.image.release=us-docker.pkg.dev/agones-images/ci --set agones.image.tag=1.30.0-655e252-amd64