feat: improve content type sys field type

[marcogrcr]

WHAT?

Improve the sys field type on content types so that they re-use the Sys type from the contentful module.

WHY?

The Sys type can change over time. For example, the current type is missing the revision, space and environment fields. By re-using there's no need to manually keep these types in sync.

HOW?

yarn test

[marcogrcr]

As a temporary workaround. Users can use this script.