Add account selection functionality to mobile navigation

Added a new type, 'Accounts', and used it to enable account selection from the mobile navigation menu. The 'Accounts' type incorporates the label, value, and image of a given account. This change will improve the app's usability, making it easier for users to navigate different accounts directly from their mobile devices. For custom plans, a null check has been implemented to avoid rendering null values.

packages/billing/gateway/src/components/plan-picker.tsx

@@ -213,7 +213,7 @@ export function PlanPicker(
                         return item.interval === selectedInterval;
                       });
 
-                      if (!plan) {
+                      if (!plan || plan.custom) {
                         return null;
                       }