Label updates in the payment gateway plugin

I think we should also consider changing the name of the class itself to MonerisCheckout instead of MonerisCheckoutOffsite unless there's precedent throughout contrib for including "Offsite" in the class name.

marchuk.vitaliy → made their first commit to this issue’s fork.

Opened MR with the fixes.

Committed!

Automatically closed - issue fixed for 2 weeks with no activity.