Improve the Wix Integrations for Flutterwave Merchants.

Todos.

1. Create a Payment Form widget for Wix. collect donations and one-time payments.

2. Create a Payment App.

https://dev.wix.com/docs/develop-websites/articles/getting-started/about-velo-by-wix

https://dev.wix.com/docs/develop-websites/articles/coding-with-velo/integrations/custom-extensions-spis/custom-app-extensions-using-spis

https://www.wix.com/velo/reference/spis/wix-payments/payment-provider

https://dev.wix.com/docs/develop-websites/articles/code-tutorials/wix-pay/tutorial-payment-provider-custom-extension