Add support for hiding the sender's email address in Bitwarden Sends

Note: The original Vaultwarden implementation of Bitwarden Send would always
hide the email address, while the upstream implementation would always show it.

Upstream PR: https://github.com/bitwarden/server/pull/1234

src/db/schemas/mysql/schema.rs

@@ -122,6 +122,7 @@ table! {
         expiration_date -> Nullable<Datetime>,
         deletion_date -> Datetime,
         disabled -> Bool,
+        hide_email -> Nullable<Bool>,
     }
 }