docs: update CamData service information

• Mark SharePoint as a legacy part of the CamData service, and explain how GCP and Google Drive are now used instead.
• Add more details about the role of the Drupal 7 server in providing the CamData service.
• Upgrade to a more recent version of Material for MkDocs, and enable the subsequently available content.tooltips theme feature.
• Fix the incorrect link between "web application deployment" page and "DNS" page.

Closes #265