Commit notes for the payment fee support

While updating RWC-330, RWC-76 was included.
Fees will only be supported in non RCO mode due to how RCO works as we very much have to create the RCO iframe before the woocommerce handlers.
getAnnuityFactors can now be chosen to display or return. See RWC-331. It can also be chosen to show product price or a custom price.
Added getResursMethodFromPrefix() to make sure we can store payment method data in an early state for the session (for fee handling mostly)
Added internal_tax setting for the fee handling. See RWC-318. This is the way we apply tax classes to the fee.
Some slugs for language fixed.
setFee changed @since because it has been activated.