this is similar to iosbuild.sh, but will create .xcframework variants to
support Catalyst targets. currently it includes libs for:
ios-arm64_armv7_armv7s
ios-arm64_x86_64-maccatalyst
ios-i386_x86_64-simulator
macos-arm64_x86_64
this script requires Xcode 12+ to target arm64 for mac/catalyst, Xcode
11 builds will create x86_64 libraries only. iosbuild.sh remains for
compatibility purposes
Change-Id: I289c54c4b85848392a99bea698d45d54a9781f49
