This is the first try of a new TabBar look - borders have been
removed, selected tab doesn't change the font to bold, adjustment
to the selected tab line.

Width and height of a tab item has been adjusted to make it
better to fit the icons in and to not be so cramped.

Draw "protected" status of an tab icon (in Calc) as an icon and
not as a unicode glyph.

Change-Id: If2ee930a573343166fbe9efcd94ae5159a620f22
Reviewed-on: https://gerrit.libreoffice.org/71238
Tested-by: Jenkins
Reviewed-by: Tomaž Vajngerl <quikee@gmail.com>