Chore: Move Mock API into separate package (#104644)

package.json

@@ -85,6 +85,7 @@
     "@grafana/eslint-config": "8.0.0",
     "@grafana/eslint-plugin": "link:./packages/grafana-eslint-rules",
     "@grafana/plugin-e2e": "2.0.0",
+    "@grafana/test-utils": "workspace:*",
     "@grafana/tsconfig": "^2.0.0",
     "@manypkg/get-packages": "^2.2.0",
     "@npmcli/package-json": "^5.2.0",