Makes Space key behavior the same as mouse click. Focus remains on the
tab button when the deck collapses.

Makes Enter key never collapses the deck but to open if collapsed and
always place focus on the first panel title.

Change-Id: Id6d7624e88b421dcfc62f3d0e79986f10c76a65d
Reviewed-on: https://gerrit.libreoffice.org/59616
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>