CKO Nuxt Module: Do not load SDKs on first load - only if requested

[Fifciu]

What is the motivation for adding / enhancing this feature?

Load SDK of payment methods only when they are needed - not on every page.

What are the acceptance criteria

• useCko should export loading methods for both Frames & Klarna SDK. Methods should return Promise which is resolved when script is loaded - so the developer can await this before mounting sdk.
• It should check whether it is already added or not. We do not want to add it multiple times. If it's already added - resolve promise instantly

Version of Vue Storefront

• Vue Storefront
• Vue Storefront Next

Can you complete this feature request by yourself?

• YES
• NO