Implementing PUT and PATCH user

To update the user, we need a page such as new_user(), but we want the form pre-populated with existing data. We also want to add another field for the user to confirm the old password. Let's look at the steps:

1. Change the edit_user() function signature to the following:

   #[get("/users/edit/<uuid>", format = "text/html")]
   pub async fn edit_user(mut db: Connection<DBConnection>,    uuid: &str, flash: Option<FlashMessage<'_>>) -> HtmlResponse {}

2. To get the existing user, append the following lines inside the function body block:

   let connection = db
       .acquire()
       .await
       .map_err(|_| Status::InternalServerError)?;
   let user = User::find(connection, uuid)
       .await
       .map_err(|_| Status::NotFound)?;

3. After that, we can append the HTML, such as new_user(),...