[ECE] Disable ECE for non-shipping products if tax is based on billing address

[asumaran]

Description

ECE is incompatible with products that do not require shipping and if the tax is calculated based on the shopper's billing address. This is because in order to show the total amount to the shopper, we have to know the billing address the user has on Apple Pay/Google Pay. We don't have that information until the user has submitted the payment sheet, which is too late to show the correct amount we will charge the user.

We will hide the button in that scenario to avoid charging the user a different amount than what was presented to them. (Although, in some cases, the final charged amount can be correct.)

Acceptance criteria

For virtual products

• ECE should not be visible if the product does not require shipping and tax is enabled and calculated based on the shopper's billing address.

For variations

• ECE should not be visible if the product does not require shipping and tax is enabled and calculated based on the shopper's billing address.
• If variation that requires shipping is selected then ECE should be visible.

Additional context

Same issue happens with PRBs #8373

[haszari]

Labelling as checkout payments based on "ECE" (aka express checkout element).