Feature: Add assets permissions

[ikovac]

This PR extends an existing storage proxy. It introduces a new storage folder structure where assets are stored under repository/repositoryId. This structure is suitable for checking asset permissions.

Todo:

• [x] Change storage folder structure
• [x] Mount assets to the repository router
• [x] Pass repositoryId to the storage proxy
• [x] Clear storage cookies on logout
• [x] Update tce-scorm to match new changes
• [x] Add migration script

Note: In order to work with the tce-scorm element this PR need to be merged: https://github.com/ExtensionEngine/tce-scorm/pull/2

Important 💥 This PR introduces breaking changes related to assets. It is necessary to run a migration script to make it work properly. Run npm run migrateAssetsLocation

[ikovac]

After conversation with @underscope, we decided to change migration logic a little bit so that we don't have to specify the exact CONTENT_ELEMENT which to migrate and rather migrate all content elements which contain assets/embeds data property.