Payment links add terms and withdrawl checkbox

[juwillsee]

@david could we get this feature back on the wishlist for Version 3 Payment Links?

Subscriptions feedbacks and questions

@s0nik42 I was never really happy with v2, we did make another iteration which may be a bit better, try appending /v3 to the subscription url instead. This one should be able to handle understanding the tax requirements as long as we capture the client data prior to the payment flow commencing.