* Add "goToCheckout" method in "shopper.block"
Instead of using "shopper.goToCheckoutBlock" method, it will much easier
to maintain the following structure "shopper.block.goToCheckout"
* Create a constant for billing details
* Create "fillBillingDetails" shopper method
* Add "placeOrder" method to "shopper"
* Enable "Cash on delivery" payment method for our test
* Update "@woocommerce/e2e-utils" package
Some new useful e2e utility functions weren't avaiable in the previous version
* Add E2E test for "Can place an order as guest"
* Fix mini-cart failing E2E tests
In case this fixwoocommerce/woocommerce-blocks#6006 isn't merged yet, this commit can be used to pass all
E2E tests
Co-authored-by: Saad Tarhi <saad.tarhi@automattic.com>