Things done in this commit:
- Created a hamburger menu button on the right.
- Moved the opening menu to match the new hamburger button.
- Added 1 pixel at the end of shortcut toolbox so no overlapping with
the tabs would occur.

Change-Id: I3d05eec72e260575563e4d016945af0777541cfb
Reviewed-on: https://gerrit.libreoffice.org/38450Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Szymon Kłos <szymon.klos@collabora.com>