E2C: Implement on-prem auth flow (#83513)

* add connection modal

* extend api with connect/disconnect endpoints

* extract translations

* display stack url

* use react-hook-form

* fix links spanning whole modal

* review comments

public/locales/en-US/grafana.json

@@ -697,10 +697,35 @@
       "link-title": "Learn about migrating other settings",
       "title": "Can I move this installation to Grafana Cloud?"
     },
+    "connect-modal": {
+      "body-cloud-stack": "You'll also need a cloud stack. If you just signed up, we'll automatically create your first stack. If you have an account, you'll need to select or create a stack.",
+      "body-get-started": "To get started, you'll need a Grafana.com account.",
+      "body-paste-stack": "Once you've decided on a stack, paste the URL below.",
+      "body-sign-up": "Sign up for a Grafana.com account",
+      "body-token": "Your self-managed Grafana installation needs special access to securely migrate content. You'll need to create a migration token on your chosen cloud stack.",
+      "body-token-field": "Migration token",
+      "body-token-field-placeholder": "Paste token here",
+      "body-token-instructions": "Log into your cloud stack and navigate to Administration, General, Migrate to Grafana Cloud. Create a migration token on that screen and paste the token here.",
+      "body-url-field": "Cloud stack URL",
+      "body-view-stacks": "View my cloud stacks",
+      "cancel": "Cancel",
+      "connect": "Connect to this stack",
+      "connecting": "Connecting to this stack...",
+      "stack-required-error": "Stack URL is required",
+      "title": "Connect to a cloud stack",
+      "token-required-error": "Migration token is required"
+    },
     "cta": {
       "button": "Migrate this instance to Cloud",
       "header": "Let us manage your Grafana stack"
     },
+    "disconnect-modal": {
+      "body": "This will remove the migration token from this installation. If you wish to upload more resources in the future, you will need to enter a new migration token.",
+      "cancel": "Cancel",
+      "disconnect": "Disconnect",
+      "disconnecting": "Disconnecting...",
+      "title": "Disconnect from cloud stack"
+    },
     "get-started": {
       "body": "The migration process must be started from your self-managed Grafana instance.",
       "configure-pdc-link": "Configure PDC for this stack",
@@ -751,6 +776,9 @@
       "link-title": "Grafana Cloud pricing",
       "title": "How much does it cost?"
     },
+    "resources": {
+      "disconnect": "Disconnect"
+    },
     "token-status": {
       "active": "Token created and active",
       "no-active": "No active token"