Add JSON-serializable output models for all Apple APIs

[rmarinho]

Summary

Define structured, JSON-serializable result types for all Apple environment and simulator management APIs. This supports the --json global option from the CLI spec.

Requirements

Every API should return a typed result that can be serialized to JSON. The output contract should include:

Standard envelope

All JSON output follows a consistent structure:

{ "type": "result", "command": "apple.check", "data": { ... } }
{ "type": "progress", "message": "Downloading iOS 18.2 runtime...", "percent": 45 }
{ "type": "error", "code": "XCODE_NOT_FOUND", "message": "..." }

Model types needed

• XcodeInfo — version, path, build number, bundled SDKs, isSelected
• SimulatorInfo — name, UDID, state, runtime, deviceType
• RuntimeInfo — platform, version, build, identifier, size, source
• EnvironmentCheckResult — xcode, clt, runtimes, platforms, overall status
• ProgressReport — message, percent, step
• ErrorResult — code, message, details

Design Notes

• Use System.Text.Json source generators for AOT-friendly serialization
• Follow the naming conventions from the CLI spec (camelCase JSON properties)
• These models are the contract between the library and the CLI — keep them stable
• Consider placing in a separate namespace (e.g., Xamarin.MacDev.Models) for clean separation

Reference

• CLI spec PR

[rmarinho]

All requirements from this issue have been implemented and merged to main across multiple PRs:

• Add ProcessUtils helper and output models for Apple CLI APIs #155 — Foundation: ProcessUtils helper + output models namespace (\Xamarin.MacDev.Models)
• Add Command Line Tools detection #156 — \CommandLineToolsInfo\ (CLT detection)
• Add Xcode management APIs #157 — \XcodeInfo\ (Xcode management)
• Add simulator management APIs #158 — \SimulatorDeviceInfo, \SimulatorDeviceTypeInfo, \SimulatorRuntimeInfo\ (simulator management)
• Add runtime management APIs #159 — Runtime management APIs with \SimulatorRuntimeInfo\
• Add environment check APIs #160 — \EnvironmentCheckResult\ (environment health check)
• Add Apple install orchestrator #161 — Apple install orchestrator (ties everything together)

All model types requested (XcodeInfo, SimulatorInfo, RuntimeInfo, EnvironmentCheckResult, CommandLineToolsInfo) are now on main under \Xamarin.MacDev/Models/.