Contributors: move to sites, change context of use

[Garneauma]

• Moved Cotnributors component to Sites section
• Updated Page details component to include Contributors component
• Updated Topic template with new Contributors location

Related to WET-505

[Garneauma]

Pre-approved upon successful review.

[duboisp]

Todo:

• Centralize sample inside the contributor component.
• (Optional) remove the "gc-" prefix in the file/folder name for the contributor component
• Update the contributor component documentation to add more emphasis on the breaking change + migration instruction.
• Page details - move demoted pattern in demoted folder
• For "contributor" component, make it a minor version for now (v1.1) because both are still ok, but identify the version 1.0 as demoted. We will increase the major version when we will switch the v1.0 from "demoted" into "deprecated" state.

This change is:

• Minor change for contributor component - Add new pattern where located in the page details section
• Minor change for page details component - Add new pattern that include the contributor component
• Minor change for Topic template - Add new pattern that include the new page details with the contributor component
• Minor change for the "Topic" template - Add new pattern that implement page-details v 3.3 where the contributor component are in the page-details section
• We will perform a major change to those component, when we will switch them from "demoted" into "deprecated" at our next major release