ci: add centraldashboard-angular tests

[andyatmiami]

related: #74

Please note this PR makes a few modifications to the workflows:

• node-version: 16 has been set for backend (previously node-version: 12 in kubeflow/kubeflow although we build on a node16 base image)
• frontend workflows have a reworked Install dependencies step that builds off PR fix(dashboard): centraldashboard-angular build with common-lib fetch #92 to ensure kubeflow-common-lib built and available
• paths updated now that the testing folder does not live under the components/ folder
• various manifests that reside in kubeflow/kubeflow under components/notebook-controller and components/crud-web-apps are provided to kustomize via their GitHub URL as those components weren't migrated to kubeflow/dashboard

TODO: Add .github/workflows/centraldb_angular_docker_publish.yaml once we are ready for publish/release.

[milinddethe15]

/ok-to-test

[andyatmiami]

Successful runs of the GHAs being added were observed (before I reverted the change to VERSION)

• https://github.com/kubeflow/dashboard/actions/runs/14864690581/job/41738410044?pr=96
• https://github.com/kubeflow/dashboard/actions/runs/14864690581/job/41738410043?pr=96
• https://github.com/kubeflow/dashboard/actions/runs/14864690566/job/41738410047?pr=96
• https://github.com/kubeflow/dashboard/actions/runs/14864690566/job/41738410063?pr=96
• https://github.com/kubeflow/dashboard/actions/runs/14864690566/job/41738410048?pr=96
• https://github.com/kubeflow/dashboard/actions/runs/14864690540/job/41738410056?pr=96

ℹ️ @thesuperzapper had mentioned some of these centraldashboard-angular tests might be flaky - but please note I did not attempt to make any improvements there as part of this PR (nor did I - in my 1 successful run - observe any failures)

[google-oss-prow]

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[juliusvonkohout]

Sorry for the delay.
/lgtm
/approve

since the KSC soon wants to remove the old code. So we must have the ci/cd in kubeflwo/dashboard working, even if it is not perfect.

@kunal-511 do you mind checking whether you can update most tests according to what we have in Kubeflow/manifests and adjusting our sychronization scripts in / scripts for synchronizing from kubeflow/dashboard and kubeflow /notebooks instead of kubeflow/kubeflow?