chore: Add campaign empty page (#2173)

* Enhancement: Create route for contact details page

* add campaign page, add button, campaign description

* add locale texts

* update locale texts

* update grid

Co-authored-by: Nithin David <webofnithin@gmail.com>

app/javascript/dashboard/i18n/locale/en/campaign.json

@@ -0,0 +1,9 @@
+{
+  "CAMPAIGN": {
+    "HEADER": "Campaigns",
+    "HEADER_BTN_TXT": "Create Campaign",
+    "LIST": {
+      "404": "There are no campaigns attached to this inbox"
+    }
+  }
+}