Stunner - disable doing operation in view mode

It shouldn't be possible doing operation like creating elements (events, activities, etc.) in view mode. Also clear diagram button should be disabled in view mode.

Acceptance test

1. create process
2. Save multiple versions
3. Select to some older version
4. Try edit diagram, check also properties dock on right side for
   • Events, Activities, SubProcesses, Gateways RHPAM-1051
5. Repeat last two steps multiple times
6. Restore to some version
7. Try edit diagram, check also properties dock on right side for
   • Events, Activities, SubProcesses, Gateways RHPAM-1051
8. Select latest version, without need to restore
9. Try edit diagram, check also properties dock on right side for
   • Events, Activities, SubProcesses, Gateways RHPAM-1051