Tagging for ftw.workspace

[shylux]

:construction_worker: :construction:

• [x] Mark workspace as tag root
• [x] Enable tagging on specified types
• [x] Register tag cloud portlets
• [ ] Restrict portlet (temporary set to content_type File)
• [x] Upgrade steps & check dependencies
• [ ] Tests

Corresponding changes in ftw.tagging: https://github.com/4teamwork/ftw.tagging/pull/3

[shylux]

Current state:

Does a test make sense? If so what should i test?

@maethu

[maethu]

@shylux also add a test if the portlet works correctly.

[shylux]

This PR is on hold because it's questionable if a tag cloud is necessary in ftw.workspace.