[AC][ApplePay]: add .applePayStyle() modifier to configure styling on ApplePay#551

kieran-osgood-shopify wants to merge 3 commits intomainShopify/checkout-sheet-kit-swift:mainfrom

issue-569-add-color-modifierShopify/checkout-sheet-kit-swift:issue-569-add-color-modifierCopy head branch name to clipboard