register missing push devices at login (#3792)

save the push token of new device even if push notifications are not
enabled and provide a way to register the push device at login

unregister device if there already is a push token saved unless the
new token has already been registered.

also the `unregister_push_device` function used the wrong argument
cf. 08d380900b/src/Core/Services/Implementations/RelayPushRegistrationService.cs (L43)

src/api/identity.rs

@@ -14,6 +14,7 @@ use crate::{
             log_user_event,
             two_factor::{authenticator, duo, email, enforce_2fa_policy, webauthn, yubikey},
         },
+        push::register_push_device,
         ApiResult, EmptyResult, JsonResult, JsonUpcase,
     },
     auth::{generate_organization_api_key_login_claims, ClientHeaders, ClientIp},
@@ -266,6 +267,9 @@ async fn _password_login(
         }
     }
 
+    // register push device
+    register_push_device(&mut device, conn).await?;
+
     // Common
     // ---
     // Disabled this variable, it was used to generate the JWT