Cloud Licensing troubleshooting - add method to activate cloud activation key via GraphQL

Why is this change being made?

Customers who have received a new activation code will typically want to activate it immediately, and having a problem doing so is a frustrating experience, especially given that the customer has already purchased the product.

This change adds a short guide on how to activate a Cloud Activation code using the GraphQL API in the event that the usual activation methods are unavailable due to an error or bug.

Related tickets: https://gitlab.zendesk.com/agent/tickets/431210

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