build: add arm64 iOS simulator NuGet RID

[Marc-André Moreau (mamoreau-devolutions)]

Summary

• add iossimulator-arm64 native builds mapped to Rust target aarch64-apple-ios-sim
• remove the old Intel simulator ios-x64 build from the native matrix
• package separate iOS device and simulator framework assets under ios-arm64 and iossimulator-arm64
• route consuming iOS simulator builds to the simulator framework in the NuGet targets

Validation

• git diff --check
• dotnet build .\ffi\dotnet\Devolutions.Sspi\Devolutions.Sspi.csproj /p:GeneratePackageOnBuild=false
• MSBuild property checks for iossimulator-arm64 and ios-arm64
• NuGet dry-run CI succeeded: https://github.com/Devolutions/sspi-rs/actions/runs/27829767516
• Downloaded dry-run package contains runtimes/ios-arm64 and runtimes/iossimulator-arm64, with no runtimes/ios-x64 or runtimes/ios-universal