Propagate `InputEvents` without position either
- during the Input-stage, when it has focus or
- during the Unhandled-Input-stage, otherwise
This makes sure that Gui-Input happens in the correct order.
Move "Unhandled key Input" handling before "Unhandled Input" handling,
so that Unicode input with Alt / Ctrl modifiers are sent to the nodes
in the correct order.
Change the default focus mode of `SubViewportContainer` from
`FOCUS_NONE` to `FOCUS_CLICK`, to automatically remove focus from
other `Control`-nodes, when clicking inside a `SubViewport`.
e6386bc843