Drop SWIG python interface

The SWIG auto-generated bindings for KiCad are not a real API and directly expose KiCad implementation details, meaning that it is essentially not possible to provide stability between KiCad versions. Providing a directly-coupled interface to KiCad also exposes the entire application to bugs in plugins (and vice versa).

We will remove SWIG (and wxPython, etc) from KiCad once a real API is available that does not expose KiCad internals and does not run plugins in the KiCad process.

KiCad Version

Application: KiCad Schematic Editor (64-bit)

Version: (5.99.0-12165-gb0ba8b01c4), debug build

Libraries:
	wxWidgets 3.1.5
	libcurl/7.78.0-DEV Schannel zlib/1.2.11

Platform: Windows 10 (build 19043), 64-bit edition, 64 bit, Little endian, wxMSW

Build Info:
	Date: Sep  1 2021 00:05:34
	wxWidgets: 3.1.5 (wchar_t,wx containers)
	Boost: 1.76.0
	OCC: 7.5.0
	Curl: 7.78.0-DEV
	ngspice: 35
	Compiler: Visual C++ 1929 without C++ ABI

Build settings:
	KICAD_USE_OCC=ON
	KICAD_SPICE=ON
	KICAD_STDLIB_DEBUG=OFF
	KICAD_STDLIB_LIGHT_DEBUG=OFF
	KICAD_SANITIZE_ADDRESS=OFF
	KICAD_SANITIZE_THREADS=OFF