[chen] make webAuth support social login

Auth0.js support social login by using 
webAuth.authorize({
  connection: 'twitter'
});
https://auth0.com/docs/libraries/auth0js/v9  
but @types/react-native-auth0 stop us to pass it in, so add "connnection" as a legal parameter

types/react-native-auth0/index.d.ts

@@ -137,6 +137,7 @@ export interface AuthorizeParams {
     nonce?: string;
     audience?: string;
     scope?: string;
+    connection?: string;
 }
 
 export interface ClearSessionParams {