Return correct product prices datatype in WCPay

Expected outcome

The multi-currency prices conversion is working as expected and prices are shown correctly after changing price values from float to string.

Testing instructions

• As a shopper go to the Shop page, switch the currency to EUR.
• Add simple product to cart.
• Add variable product to cart.
• Add sale product to cart.
• Switch currencies to JPY and USD and see that the prices are shown correctly.
• Checkout and Pay, should be good without errors.

Be able to access Subscription details when purchased via SEPA Direct Debit

Expected outcome

Merchants can access subscription details after shoppers pay by using SEPA Direct Debit.

Testing instructions

1. As a merchant, create a subscription with WooCommerce Subscriptions
2. Enable SEPA Direct Debit as a payment option. See guide here if needed.
3. Purchase the subscription in step 1 with a test account number.
4. Navigate to WooCommerce > Subscriptions and select the subscription purchased in step 3.
5. The page should be loaded without any issue. Check in the browser console, there is no 500 error like this.