Rework Connect toolbar button usage

Don't use native widget siblings

Adding Issue #1157 to put back

QQuickWidget can’t handle this

Now works for more than Serial links

Move ui style from MainWindow to QGCApplication

Moving more things off of MainWindow

Moving methods from MainWindow to QGCApplication so that more things
can run without a window. Helpful for testing.

Setup work

Emitting signal beforehand can lead to subtle bugs where code expects
value to be updated and it is not.

Summary buttons in Qml

Safety component

Fix intermittent UT failure

Fact controls

Safety config starting point