Rename createUser to newUser for consistency

src/graphql.rs

@@ -492,7 +492,7 @@ pub struct Mutation;
 
 #[graphql_object(context = Context)]
 impl Mutation {
-    async fn createUser(context: &Context, new_user: NewUser) -> FieldResult<ID> {
+    async fn newUser(context: &Context, new_user: NewUser) -> FieldResult<ID> {
         let user: User = new_user.clone().into();
         if !is_valid_user_name(&user.user_name) {
             return Err(format!("{:?} is not a valid username", user.user_name).into());