Update to use the JavaScript SDK integration

[Pebblo]

Garth ran into some issues with Venmo on Event Smart and it looks like it might be from using a deprecated integration.

It looks like we currently use the deprecated checkout.js integration:
https://developer.paypal.com/docs/archive/checkout/

Can we look into switching over to the JavaScrip SDK? This is what I found which I think is related:
https://developer.paypal.com/docs/checkout/standard/upgrade-integration/#checkoutjs-integrations-with-actionspaymentcreate

[garthkoyle]

I wonder if we want to forego doing this and just take the opportunity to move to PayPal Commerce: https://p2.eventespresso.com/2020/05/19/evaluating-paypal-commerce-as-a-new-integration/

[tn3rb]

moving to PayPal Commerce is a great idea ➕ 👍🏻