* Add testmode-support-flag to SalesChannels
* Make saleschannels/testmode-warnings even more dangerous!
* Add warning for payment-methods that do support testmode but are being used in a non-testmode order caused by a saleschannel in a testmode-shop.
* Remove redundant testmode_supported-flag for WebshopSalesChannel
* Raise error on API when sales_channel does not support testmode
* Tests
* Fix style issue after merge