fix: check whether org exists before creating user (#11647)

# Which Problems Are Solved

It was possible to create a user with an imaginary org.

# How the Problems Are Solved

Check whether org exists before creating the user.

# Additional Changes


# Additional Context

- Closes #11532

internal/command/user_machine.go

@@ -114,6 +114,10 @@ func (c *Commands) AddMachine(ctx context.Context, machine *Machine, state *doma
 			return nil, err
 		}
 	}
+	err = c.checkOrgExists(ctx, machine.ResourceOwner)
+	if err != nil {
+		return nil, err
+	}
 	cmds, err := preparation.PrepareCommands(ctx, c.eventstore.Filter, AddMachineCommand(agg, machine))
 	if err != nil {
 		return nil, err