New build-ios-arm64.sh for iOS target now that Apple Store Monopoly no longer rules Europe

[gubatron]

See https://github.com/frostwire/frostwire-jlibtorrent/pull/288/files
CC FunkyMuse

[gubatron]

CoPilot Changes Summary:

This pull request introduces a new build script for iOS on ARM64 architecture and updates the build utilities to support this new target. The most important changes include the addition of the iOS build script, the new environment configuration for iOS, and modifications to the build utilities to handle iOS builds.

New iOS Build Script:

• swig/build-ios-arm64.sh: Added a new script to build the Java JAR and iOS (.dylib) JAR for ARM64 architecture. This script sets up the necessary environment and runs the build process.

Environment Configuration for iOS:

• swig/build-utils.shinc: Introduced ios_env() function to set up the environment variables specific to iOS builds, including paths and compiler flags.

Build Utilities Update:

• swig/build-utils.shinc: Modified build_libraries() to handle the renaming and copying of the shared library for iOS builds, similar to the existing macOS logic.

iOS Configuration:

• swig/config/ios-arm64-config.jam: Added a new configuration file for building with the darwin toolset targeting ARM64 architecture, specifying necessary compiler flags.