feat: add loading state and full-page loader component; update payment page and application layout to improve user experience

app/(dashboard)/devices-to-pay/loading.tsx

@@ -0,0 +1,8 @@
+import FullPageLoader from '@/components/full-page-loader'
+import React from 'react'
+
+export default function Loading() {
+  return (
+    <FullPageLoader />
+  )
+}