Support EU Data Center

[Swissbite]

Contentful added the support to host an organisation within the EU, see https://www.contentful.com/developers/docs/infrastructure/eu-data-residency/

Therefore, the endpoints for the API in EU changed:

API	URL
Content Management API	https://api.eu.contentful.com
Content Delivery API	https://cdn.eu.contentful.com
Content Preview API	https://preview.eu.contentful.com
GraphQL API	https://graphql.eu.contentful.com
Images API	https://images.eu.ctfassets.net
User Management API	https://api.eu.contentful.com

Suggestion:

• Add an additional and optional flag where the endpoint is in "EU" or not.

Alternative:

• Option to overwrite the host itself, as it is defined in the contentful-export library, see https://github.com/contentful/contentful-export#host-string-default-apicontentfulcom

[marcolink]

@Swissbite would that solve the issue?

[Swissbite]

@marcolink Yes, I can confirm that the solution with #325 will solve the issue.