Fix the prologue buttons background color when using a dynamic color

[rachelmcr]

Part of: woocommerce/woocommerce-ios#3824

Description

In LoginPrologueViewController, we have the option to provide a background color for the prologue buttons and have that background color extend the full width of the screen (when buttonsBackgroundColor and prologueViewBackgroundColor are the same color).

However, setting that background color to a dynamic color breaks the behavior in the same way as in the original issue woocommerce/woocommerce-ios#3319.

Changes

In #539, the fix for woocommerce/woocommerce-ios#3319 includes a check to compare prologueViewBackgroundColor and buttonsBackgroundColor, to determine if the blur effect should be applied or if the view's background color should be set.

However, that compares the UIColor objects, which may be different even if their color values are the same. This PR compares the CGColor value instead, to ensure we're doing a valid comparison of the color data.

/	Before	After
Light
Dark

Testing

Build and run the app from the branch in WooCommerce that uses these changes, to confirm the background looks as expected in light and dark mode: https://github.com/woocommerce/woocommerce-ios/tree/issue/3824-prologue-carousel

[ctarda]

Fantastic!

Thanks for preparing a branch in WooCommerce to test this. This is how the login prologue looks for me: