Provide support for iOS wheels

Expected behaviour

Would it be possible to add support to target iOS with:

• iphoneos arm64
• iphonesimulator arm64
• iphonesimulator x86_64

OpenCV for iOS is distributed as a framework and it's working well. So it should be possible to modify the Python part to build it.

Actual behaviour

All attempts at building failed.

Issue submission checklist

• This is not a generic OpenCV usage question (looking for help for coding, other usage questions, homework etc.)
• I have read the README of this repository and understand that this repository provides only an automated build toolchain for OpenCV Python packages (there is no actual OpenCV code here)
• The issue is related to the build scripts in this repository, to the pre-built binaries or is a feature request (such as "please enable this additional dependency")
• I'm using the latest version of opencv-python

Inizia esaminando gli script di build Python del repository e la toolchain CI automatizzata per determinare come sono configurati i target delle piattaforme e le build dei framework. Confronta il flusso di build attuale con i target richiesti iphoneos arm64, iphonesimulator arm64 e iphonesimulator x86_64; il lavoro è completato quando vengono prodotti correttamente wheels iOS supportati per tutti e tre.