feat: Prevent saving preferences and status when impersonating (#11164)

This PR will prevent saving user preferences and online status when impersonating. Previously, these settings could be updated during impersonation, causing the user to see a different view or UI settings.

Fixes https://linear.app/chatwoot/issue/CW-4163/impersonation-improvements

app/javascript/dashboard/composables/useImpersonation.js

@@ -0,0 +1,10 @@
+import { computed } from 'vue';
+import SessionStorage from 'shared/helpers/sessionStorage';
+import { SESSION_STORAGE_KEYS } from 'dashboard/constants/sessionStorage';
+
+export function useImpersonation() {
+  const isImpersonating = computed(() => {
+    return SessionStorage.get(SESSION_STORAGE_KEYS.IMPERSONATION_USER);
+  });
+  return { isImpersonating };
+}