VP1Base: fix some missing signal/slot errors
This fixes the following:
[vp1/stderr] QObject::connect: No such slot VP1TabBar::VP1TabBar::activateDragSwitchTab() in /build1/atnight/localbuilds/nightlies/Athena/main/athena/graphics/VP1/VP1Base/src/VP1TabBar.cxx:78
[vp1/stderr] QObject::connect: No such signal VP1TabBar::VP1TabWidget::moveTab( int, int ) in /build1/atnight/localbuilds/nightlies/Athena/main/athena/graphics/VP1/VP1Base/src/VP1TabWidget.cxx:177
[vp1/stderr] QObject::connect: (receiver name: 'tabbar')
[vp1/stderr] QObject::connect: No such signal VP1TabBar::VP1TabWidget::wheelDelta( int ) in /build1/atnight/localbuilds/nightlies/Athena/main/athena/graphics/VP1/VP1Base/src/VP1TabWidget.cxx:180
[vp1/stderr] QObject::connect: (receiver name: 'tabbar')
See ATLASVPONE-653 for details
cc @rbianchi