[Stripe] Enable automatic tax on transactions

[jankeromnes]

Is your feature request related to a problem? Please describe

We've now configured and enabled Stripe Tax in production:

The last step is to follow this guide in order to enable automatic tax on all transactions.

Describe the behaviour you'd like

• Configure and enable Stripe Tax
• Add a "tax behavior" to every Price (and optionally a "tax category" to every Product)
• If possible, set the correct customer.address on Customer creation
  • Note: the payment method input form already asks users for a country -- can we simply re-use that?
• When creating a Subscription, set automatic_tax: {enabled: true} (when supported)
• Confirm that automatic tax collection works in production (e.g. when invoices are finalized at the end of a month)

Describe alternatives you've considered

• Do all taxes manually for each customer 😱

Additional context