Add Zone cutout doesn't check that it has a point in the zone

Description

After creating a filled zone, we can add a zone cutout using the hotkey (default Shift-C). If the zone cutout doesn't overlap the originally-selected zone, we clear the whole zone and it is difficult to fix without reloading.

Steps to reproduce

1. Create a filled zone.
2. With the filled zone selected, move your mouse outside of the zone area
3. Create a cutout that doesn't overlap the original zone outline

KiCad Version

Application: Pcbnew

Version: (5.99.0-3190-g7b05e456c-dirty), debug build

Libraries:
	wxWidgets 3.0.5

Platform: Linux 5.7.0-3-amd64 x86_64, 64 bit, Little endian, wxGTK

	wxWidgets: 3.0.5 (wchar_t,wx containers,compatible with 2.8) GTK+ 3.24
	Boost: 1.71.0
	OCC: 7.4.0
	Curl: 7.72.0
	ngspice: 32
	Compiler: GCC 10.2.0 with C++ ABI 1014

Build settings:
	KICAD_SCRIPTING=ON
	KICAD_SCRIPTING_MODULES=ON
	KICAD_SCRIPTING_PYTHON3=ON
	KICAD_SCRIPTING_WXPYTHON=ON
	KICAD_SCRIPTING_WXPYTHON_PHOENIX=ON
	KICAD_SCRIPTING_ACTION_MENU=ON
	BUILD_GITHUB_PLUGIN=ON
	KICAD_USE_OCC=ON
	KICAD_SPICE=ON
	KICAD_STDLIB_DEBUG=ON
	KICAD_SANITIZE=OFF