Factor out payment processor views into seperate view files.

This prevents errors in attribute_cookie_data from rolling back all basket-related transactions.

basket-related transactions.
ECOM-6387

- Using `cache.delete` rather than `caches['default']`
- Added tests

OPS-1891

The creation/modification of Source and PaymentEvent objects has been moved to the locations in the code base responsible for triggering the processing of payment processor responses and issuing credits. This move ensures that payment processors are responsible solely for processing payments. All administrative work will be handled outside of the payment processor classes.

SOL-2125

Add management command for adding site to referrals without sites

Adding logs for payment processors

Add custom verification status exception.

The current naming can be confusing and cause issues in the future.

Instead of catching and communicating back three different exceptions
that practically mean the same, we want one that indicates there was
a verification status error.

[SOL-2138] Multi-use coupon max_uses field displays incorrect value fix

[SOL-2137] Add Backend Validation for Coupon Creation - Benefit Value

- The admin pages now display the refund/line creation and modification dates.
- Items on the refund dashboard can be sorted by date of creation.
- The status filter is now exposed by default.

Re-revert enrollment request fail log message

ECOM-4763

The order field is now a raw ID field. This avoids attempts to load all orders when an administrator attempts to view an item.

This change will allow developers to continue using any desired IP/hostname during development.

[SOL-2111] Add Backend Validation for Coupon Creation - Benefit Type

Fixes the CSS of the error page.

Change is_verified to account for not found verifications.

This commit fixes a bug where an exception is raised when no
verifications where found on LMS for a specific user, that was
not caught before.

https://openedx.atlassian.net/browse/SOL-2135

SOL-2125

[SOL-2134] Add error message template.

An increasing number of apps are displaying error message by copying
the structure of the coupon error message. This commit introduces a
general template for displaying error regardless of application.

https://openedx.atlassian.net/browse/SOL-2134

[SOL-2126] Add a check for user verification status

SOL-2116

Add missing migration for verbose_name alter

Catch exceptions during paypal payment creation and introduce retry

ECOM-5891