Successful Checkout using the Store API and Basic Cards

[asumaran]

• Consolidate .env usage on local and Vercel. #2
• Get wc_store_api nonce from the API server #3
• Persist user session on the browser. #4
• Implement checkout of virtual product using Card payment method. #5
• Ability to submit new order with stored user session. #6
• Implement checkout with shipping #7