UFZ: Make externel dependencies of frontend to interal

Description

• The CSP header of the frontend included https://cdn.jsdelivr.net/
• At the ufz we try to avoid external dependencies because of the following reasons:
  • User and usage tracking by Google & Co
  • Security concerns (especially when using external JS)
• The aforementioned csp header is only used by the styleguidist to include material design icons using https://cdn.jsdelivr.net/npm/@mdi/font@5.9.55/css/materialdesignicons.min.css

Tasks

• include the material design icon dependencies (including fonts) directly in the frontend