add linkedin as oauth integration

backend/oauth_connect.json

@@ -71,5 +71,10 @@
     "extra_params": {
       "type": "web_server"
     }
+  },
+  "linkedin": {
+    "auth_url": "https://www.linkedin.com/oauth/v2/authorization",
+    "token_url": "https://www.linkedin.com/oauth/v2/accessToken",
+    "scopes": ["w_member_social"]
   }
 }