Synchronize or remove customer email from Stripe

[waiting-for-dev]

We're pushing the user or guest order email to Stripe when creating a Stripe::Customer object. However, we're not syncing when we receive the customer.updated webhook event or change the user email from Solidus.

We have two options:

• Handle the two-way sync.
• Remove pushing the email information to Stripe, as that's not a required field. Although it might be useful to quickly retrieve payments for a given user, an operator still has two ways to do that:
  • From Solidus, listing all the orders for a given user.
  • From Stripe, clicking on the customer id for a given payment intent.