Checkout - Allow EasyInvoice Client ID on Demo Page, Improve Client ID guidance on Playground page

[MantisClone]

Problems

Problem 1

Users cannot view their Checkout payments and receipts in EasyInvoice because Request Checkout uses a hard-coded EasyInvoice Client ID; therefore, all payments and receipts appear under an EasyInvoice account controlled by the Request Network Foundation.

Problem 2

On the Playground Page, users are prompted to enter their Client ID as a required field, but are not offered guidance on how to obtain a Client ID if they don't already have one.

Solution

• Users should be able to enter their Client ID on the Demo Page so that their payments and receipts created via Checkout are visible in the on their Merchant Dashboard in EasyInvoice.
• Users should see guidance explaining how to obtain a Client ID if they don't already have one on both the Demo Page and the Playground Page.

"Get your Client ID on EasyInvoice! /^