[TASK] Frontend should leverage `workspaceCounts` attribute in `/workspacekinds` API response

[andyatmiami]

🛑 Blocked by #368

Description

Historically, the Workspace Kinds overview table in the frontend has had a Number of workspaces column that lists the number of workspaces deployed that reference the given WorkspaceKind. Recent work to the frontend has also exposed counts per imageConfig and per podConfig.

• ⚠ Note that "counts per Namespace" is also shown in the UI but presently not calculated by the controller - so we will consider that out of scope to this work.

Existing logic in which frontend does the counting calculation can be seen here:

• https://github.com/kubeflow/notebooks/blob/notebooks-v2/workspaces/frontend/src/app/pages/WorkspaceKinds/WorkspaceKinds.tsx#L67
• https://github.com/kubeflow/notebooks/blob/notebooks-v2/workspaces/frontend/src/app/hooks/useWorkspaceCountPerKind.ts

The focus of this task is then to ensure the UI does not need to perform this counting logic on the client side - instead relying on the information exposed from the GET /workspacekinds API.

Please see the image included in this comment for a visual overview of how/where this counting information is being surfaced.

Acceptance Criteria

• The Number of workspaces column in the Workspace Kinds table pulls its value from the API response to GET /workspacekinds
• The number of workspaces value in the Workspace Kind imageConfig detail tab pulls its value from the API response to GET /workspacekinds
• The number of workspaces value in the Workspace Kind podConfig detail tab pulls its value from the API response to GET /workspacekinds

[andyatmiami]

/area v2
/area frontend

[caponetto]

/assign