Add hashnode support for posts plugin and additional options (#165)

source/plugins/posts/queries/hashnode.graphql

@@ -0,0 +1,12 @@
+query PostsHashnode {
+  user(username: "$user"){
+    publication{
+      posts(page: 1) {
+        title
+        brief
+        coverImage
+        dateAdded
+      }
+    }
+  }
+}