fix: MJPEG video streaming and xcode-select detection on modern macOS

[amilich]

Two key fixes for idb_companion on macOS 12.1+:

1. FBSimulatorVideoStream.m: Don't require hardware-accelerated encoding for JPEG

   • The original code unconditionally required hardware acceleration on macOS 12.1+
   • JPEG encoding may not have hardware encoder support on all systems
   • This caused VTCompressionSessionCreate to fail with -12902 (kVTParameterErr)
   • Now only H.264 requires hardware acceleration; JPEG prefers but doesn't require it

2. FBXcodeConfiguration.m: Fall back to xcode-select -p for developer directory

   • The symlink at /var/db/xcode_select_link no longer exists on modern macOS
   • Now tries the symlink first, then falls back to running xcode-select -p

3. FBSimulatorControl.xcodeproj: Mark required headers as Public

   • FBSimulatorApplicationCommands.h and FBSimulatorFileCommands.h need to be public
   • Required for idb_companion to build against the framework

4. Applied fixes from upstream PRs Fix up compiler errors #889 and Fix createGzipForPath compile failure #895 for compilation issues

These fixes enable MJPEG video streaming at ~30 FPS without requiring the simulator window to be visible on screen.

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