Fixes#3921
Added a new set of icons and removed the old one. The new one can used just like the old one.
Changed old improper icons to new ones
- The 'save_alt'-icons are replaced by 'cloud_upload'
- The icon in the navigation for assignments is replaced by 'how_to_vote'
- The drag&drop icon 'unfold_more' is replaced by 'drag_indicator'
- Projector base template
- Projection button
- projection dialog
- motion slide (template and motions/projector.py)
- user slide (template and users/projector.py)
- motion and user list view with projector column permission check.
Ports the "Motion Catalog Content Provider" to OpenSlides 3.
Categories and Prefixes are considered as before.
Updated to Code to ES6/Typescript.
Allows to export all motions from the motion list view.
