Currently, the iOS FFmpeg provisioning script will install .xcframework
files into a subfolder 'frameworks'. The .xcframework files fulfill a
similar purpose to ordinary .dylib files and should be placed in a
'lib' subfolder, to make provisioning more similar to how we deploy
FFmpeg for other platforms.
This patch makes us install .xcframework files in a 'lib' subfolder
instead.
Task-number: QTBUG-136480
Pick-to: 6.11 6.10
Change-Id: I91f9938b595ecff5b04d49a71e9872f5d7278cda
Reviewed-by: Artem Dyomin <artem.dyomin@qt.io>