The patch adds "show_tabs" command line option for GTK ui similar to
"grab_on_hover". This option allows tabbed view mode to not have to be
enabled by hand at each start of the VM.

Signed-off-by: Felix "xq" Queißner <xq@random-projects.net>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20220712133753.18937-1-xq@random-projects.net>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>