PhysX iOS platform support

What's new?

Added iOS platform support to PhysX 5.1.
New build preset ios64 added. Initial support focused on 64-bit arm8 architecture with NEON SIMD instructions.
Support for generating PhysX as either static libraries or iOS frameworks.
New iOS platform readme.

The following points are considered out of scope, they can be added in the future:

The name of the bin folder for iOS will appear as bin\UNKNOWN. To fix this nVidia has to modify the CMakeModules package it's downloaded from packman when building PhysX. The file that needs to be modified is GetCompilerAndPlatform.cmake, adding the following lines to the if condition inside GetPlatformBinName function:

	ELSEIF(TARGET_BUILD_PLATFORM STREQUAL "ios")
		SET(RETVAL "ios.arm_${LIBPATH_SUFFIX}")

Python package used by packman is based on x86_64 architecture and generates the error dyld[number]: missing symbol called when run on an arm-based Mac. To fix this nVidia has to add an ARM python package for mac into the packman scripts. As a temporary solution, use your system's python adding the environment variable PM_PYTHON_EXT before building (for example by adding export PM_PYTHON_EXT="python3" into your .bash_profile file).
PhysX Systems that require a CUDA capable GPU are not supported in iOS, for example particle system or cloth simulation.

Built PhysX 5.1 successfully on iOS in debug, checked, profile and release using PX_GENERATE_STATIC_LIBRARIES set to both true and false. The right output binaries were generated in bin/ios.arm_64
Built cmake install target successfully. It generated the correct output for iOS under install/ios64 folder, only including necessary headers for iOS.
Runtime tested using Open 3D Engine (O3DE) with an early integration branch. The following video shows O3DE running PhysX 5.1 on iOS. https://user-images.githubusercontent.com/27999040/204574141-2e00c7bf-86b5-4e14-981f-6b80665a3ef7.mp4

Signed-off-by: moraaar [email protected]