3D viewer: Add option to turn off selection highlight

Description

Because incorrect highlighting (see #5828 (closed)) cannot be fixed from kicad side (VGA driver bug), it would be nice to have an option to turn 3D highlighting off, or switch between selection modes (bounding box highlight, as @KammutierSpule). I think many intel (or dell) VGA users will suffer from this after v6 becomes public.

Steps to reproduce

1. See #5828 (closed)

KiCad Version

Application: KiCad 3D Viewer (64-bit)

Version: (5.99.0-10483-ga6ad7a4a70), release build

Libraries:
	wxWidgets 3.1.4
	libcurl/7.74.0-DEV Schannel zlib/1.2.11

Platform: Windows 10 (build 19042), 64-bit edition, 64 bit, Little endian, wxMSW

Build Info:
	Date: May  2 2021 21:02:39
	wxWidgets: 3.1.4 (wchar_t,STL containers)
	Boost: 1.75.0
	OCC: 7.5.0
	Curl: 7.74.0-DEV
	ngspice: 34
	Compiler: Visual C++ 1928 without C++ ABI

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
	KICAD_USE_OCC=ON
	KICAD_SPICE=ON