Exclude Name from Billing + Shipping Addresses

[n7studios]

Summary

Adds an option to exclude the name from the billing and shipping address when stored as custom fields in ConvertKit, as requested here.

Testing

Added the following tests to confirm the name is excluded from the address custom field when this setting is enabled:

• testSendPurchaseDataWithCustomFieldsAndExcludeNameFromAddressOnSimpleProductCheckout
• testOptInWhenCheckedWithFormCustomFieldsAndExcludeNameFromAddressOnSimpleProduct
• testOptInWhenCheckedWithFormCustomFieldsAndExcludeNameFromAddressOnSimpleProduct
• testOptInWhenCheckedWithFormCustomFieldsAndExcludeNameFromAddressOnSimpleProduct
• testOptInWhenCheckedWithFormCustomFieldsAndExcludeNameFromAddressOnSimpleProduct

Checklist

• I have written a test and included it in this PR
• I have run all tests and they pass
• The code passes when running the PHP CodeSniffer
• Code meets WordPress Coding Standards for PHP, HTML, CSS and JS
• Security and Sanitization requirements have been followed
• I have assigned a reviewer or two to review this PR (if you're not sure who to assign, we can do this step for you)