Create pods tab under Kubernetes overview

What does this MR do and why?

This MR updates the Kubernetes overview on the Environments page to show more information on the Kubernetes pods. We are adding a separate tab for the Kubernetes pods and moving the existing stats over to the new tab. This MR waits for !142203 (merged) to get ready to avoid having conflicts and reduce the changes in a single MR. It is also blocked by !142324 (merged) to ensure visual consistency between the pods and services tabs.

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

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Before	After

How to set up and validate locally

Prerequisites:

• NGINX, loopback interface, and HTTPS set up on your GDK
• Docker instance

1. Visit the Environments page:

   • Project -> Operate -> Environments if the new navigation is enabled
   • Project -> Deployments -> Environments if the new navigation is not enabled

2. Create/Edit an environment using the UI

3. Enable KAS on your GDK (steps 1-2 from the guide).

4. Visit the Project -> Infrastructure -> Kubernetes clusters page and create an agent following the instruction from the modal.

   • Select the "Connect a cluster" button
   • The modal should pop up
   • In the modal select "Select an agent or enter a name to create new"
   • You probably won't have any configured agents to show up in the list, create a new one by typing the name of your choice
   • The button should appear at the bottom of the list saying "Create agent: <your-agent-name>"
   • Select the button and click "Register" in the next view.
   • Save the token to use it in the next point.

5. Add the following configuration inside your project in .gitlab/agents/<your-agent-name>/config.yaml for the user_access agent:

   gitops:
     manifest_projects:
     - id: <your-group>/<your-project>
   user_access:
     access_as: 
       agent: {}
     projects:
     - id: <your-group>/<your-project-to-share-agent-with>

6. Note that the shared agents should be connected to the cluster in order to appear in the list. Please follow points 3-8 from the guide and then the Deploy the GitLab Agent (agentk) with k3d section to create a local cluster and connect your agent with the cluster.

7. Select an agent from the dropdown, and select a namespace in the Environments settings page and save the change.

8. Visit the Environments page and select the environment that has an associated agent.

9. Validate the pods tab

Related to #438018 (closed)