[clr-ios] Generate runtime packs for Apple mobile RIDs

[kotlarmilos]

Description

rovide runtime packs for ios-arm64, iossimulator-*, tvos-*, and maccatalyst-* that include the interpreter-enabled runtime, native libraries, BCL libraries, and Crossgen2 host tools.

Tasks

• Define pack layout per RID, such as native libcoreclr.dylib + interpreter, native deps, BCL, configuration
• Include Crossgen2 host tools for osx-arm64 and osx-x64
• [ios-clr] Enable building CoreCLR runtime packs for Apple mobile #120444
• [clr-ios] Support targeting Apple mobile platforms with CoreCLR sdk#51429

[rolfbjarne]

This will unblock dotnet/macios#21627.