Orders creation with invalid payment methods

[aftermath2]

Describe the bug

It is possible to create fiat orders with swap payment methods, and swap orders with fiat payment methods.

To Reproduce
Steps to reproduce the behavior:

1. Go to the "Create" window
2. Enable advanced options
3. Check the "Swap?" checkbox
4. Select a payment method
5. Uncheck the "Swap?" checkbox
6. See the error

To reproduce the error the other way around, do 4 before 3 and omit 5.

Expected behavior

The payment methods list is cleared when switching from fiat to swap orders and vice-versa.

Screenshots