feat: [M3-6965] - Update api-v4 and mocks for DC-specific pricing

[mjac0bs]

Description 📝

Updates api-v4 types and mocks for expected DC-specific pricing changes to API responses.

Note: #9572 includes the api-v4 updates for adding region_prices to a Linode; I'll pull those changes in once that PR is merged.

How to test 🧪

1. How to setup test environment?

• Turn the Mock Service Worker on.
• Ensure the DC-Specific Pricing flag is on.

4. How to verify changes?

• With mocks on, go to the following pages and confirm using the browser dev tools' network tab that the API responses returned for the following endpoints have the data you'd expect based on the example payload in the API spec. The API spec is linked in this ticket or the epic.:
  • Linode Create: confirm backups has added region_prices list for the linode/types endpoint
  • MNTP dialog: confirm region_transfers has been added to the account/transfers endpoint
  • Invoice Details (go to http://localhost:3000/account/billing/ and click on an invoice): confirm region has been added for the account/invoices/:id/items endpoint

[cpathipa]

LGTM!

[bnussman-akamai]

🚀