+ added registry entry for storing current toolbar mode
  for each application
+ registry entries to store toolbar mode configuration,
  remember additional visible toolbars activated by user
+ changing toolbar mode hides and shows suitable toolbars
+ added menu controller for toolbar mode
+ notebookbar implementation entries are disabled when
  notebookbar mode is not active
+ each mode can open/collapse the sidebar

Change-Id: I2b03f87c6dce53190d12102892d9ad30fbfd3bf6
Reviewed-on: https://gerrit.libreoffice.org/27991Reviewed-by: Samuel Mehrbrodt <s.mehrbrodt@gmail.com>
Tested-by: Samuel Mehrbrodt <s.mehrbrodt@gmail.com>