Link missing frameworks/libraries and flags in iOS CMake

Qt iOS CMake's users must fix linking errors of type "undefined reference" by adding extra flags.

Frameworks:

"-framework UIKit"
"-framework AssetsLibrary"
"-framework OpenGLES"
"-framework Foundation"
"-framework QuartzCore"
"-framework CoreFoundation"
"-framework CoreText"
"-framework CoreGraphics"

3rd party libraries:

"z"

Qt libraries (+ debug variant):

"libqtharfbuzzng.a"
"libqtpcre.a"
"libQt5PlatformSupport.a"

Flags (+ debug variant):

"-force_load libqios.a"

To avoid repetition of this code in every user's application this flags should be added to INTERFACE_LINK_LIBRARIES properties of Qt's targets (like Qt5::Widgets).