/app/status API that returns detailed app status

[divolgin]

What this PR does / why we need it:

• Adds API for querying details application status.
• Adds "version" key to mock data to maintain backwards compatibility. Empty string implies "v1".

# curl http://replicated:3000/api/v1/app/status | jq
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100   232  100   232    0     0  65536      0 --:--:-- --:--:-- --:--:-- 77333
{
  "appStatus": {
    "appSlug": "okteto-app-metrics",
    "resourceStates": [
      {
        "kind": "deployment",
        "name": "alpine-app",
        "namespace": "okteto-app-metrics",
        "state": "ready"
      }
    ],
    "updatedAt": "2024-12-19T23:01:52.207162284Z",
    "state": "ready",
    "sequence": 268
  }
}

Which issue(s) this PR fixes:

Fixes https://app.shortcut.com/replicated/story/116585/expose-granular-statusinformer-details-in-the-sdk-api-endpoints-available-in-the-cluster

Special notes for your reviewer:

Steps to reproduce

Does this PR introduce a user-facing change?

Adds /app/status API that returns detailed application status information.

Does this PR require documentation?

replicatedhq/replicated-docs#2917