[msbuild] Have XcodeCompilerToolTask use xcrun to start Apple tools

[spouliot]

1. Use xcrun to run ibtool (and actool) and avoid toolchain mismatches

2. Set DEVELOPER_DIR so everyone (well xcrun) use the same toolchain

3. Workaround for macos-arm64 issue (FB8827920)

   • Start ibtool as an Apple [Silicon] process
   • This will ensure the ibtoold daemon is also running as Apple
   • If ibtoold is run as Intel then ibtool asserts and build fail

LaunchScreen.storyboard : error : 2020-10-26 14:24:52.757 ibtoold[37142:6681382] [MT] DVTAssertions: Warning in /Library/Caches/com.apple.xbs/Sources/IDEInterfaceBuilder/IDEInterfaceBuilder-17506/InterfaceBuilderKit/Utilities/IBAbstractInterfaceBuilderPlatformToolManager.m:481
LaunchScreen.storyboard : error : Details:  Failed to attach to IBAgent-iOS with error: Error Domain=com.apple.InterfaceBuilder Code=-1 "Encountered an error communicating with IBAgent-iOS." UserInfo={NSLocalizedFailureReason=IBAgent-iOS (37146) failed to launch and exited with status 10, NSUnderlyingError=0x7fa4e58fc760 {Error Domain=com.apple.InterfaceBuilder Code=-1 "Failed to launch IBAgent-iOS via CoreSimulator spawn" UserInfo={NSLocalizedDescription=Failed to launch IBAgent-iOS via CoreSimulator spawn, NSUnderlyingError=0x7fa4e5e8a900 {Error Domain=com.apple.InterfaceBuilder Code=-1 "Failed to handshake with platform tool" UserInfo={NSLocalizedFailureReason=Failed to open connection over FIFOs with platform tool, NSLocalizedDescription=Failed to handshake with platform tool, NSUnderlyingError=0x7fa4e5e237c0 {Error Domain=com.apple.InterfaceBuilder Code=-1 "" UserInfo=0x7fa4e5e8bba0 (not displayed)}}}}}, NSLocalizedRecoverySuggestion=Please check Console.app for crash reports for "IBAgent-iOS" for further information., NSLocalizedDescription=Encountered an error communicating with IBAgent-iOS.}
LaunchScreen.storyboard : error : Object:   <IBCocoaTouchToolManager>
LaunchScreen.storyboard : error : Method:   +_THREADSAFE_launchNewToolWithLaunchContext:executionContext:toolProxyClass:proxyDelegate:failureContext:requestingMethod:error:forReason:
LaunchScreen.storyboard : error : Thread:   <NSThread: 0x7fa4e341af70>{number = 1, name = main}
LaunchScreen.storyboard : error : Please file a bug at https://feedbackassistant.apple.com with this warning message and any useful information you can provide.
LaunchScreen.storyboard : error : 2020-10-26 14:24:52.766 ibtoold[37142:6681382] [MT] IBPlatformTool: *** Failed to launch tool with description <IBCocoaTouchPlatformToolDescription: 0x7fa4e5f34160> System content for IBCocoaTouchFramework-fourteenAndLater <IBScaleFactorDeviceTypeDescription: 0x7fa4e5f2fb50> scaleFactor=2x, renderMode.identifier=(null): Encountered an error communicating with IBAgent-iOS. (Failure reason: IBAgent-iOS (37146) failed to launch and exited with status 10): Failed to launch IBAgent-iOS via CoreSimulator spawn: Failed to handshake with platform tool (Failure reason: Failed to open connection over FIFOs with platform tool): : Failed to open FIFOs for handshaking with platform tool (Failure reason: IBAgent-iOS exited before we could handshake)
/Library/Frameworks/Mono.framework/External/xbuild/Xamarin/iOS/Xamarin.iOS.Common.targets(1425,3): error : ibtool exited with code 1
/Library/Frameworks/Mono.framework/External/xbuild/Xamarin/iOS/Xamarin.iOS.Common.targets(1425,3): error :
LaunchScreen.storyboard : ibtool error : Encountered an error communicating with IBAgent-iOS.

Note: main has diverged quite a bit (net6 support) so this pull request
will need to be re-worked (it won't apply)

Fixes #4634

[rolfbjarne]

I think this would look a bit better:

unsafe static extern int sysctlbyname (/* const char */ [MarshalAs (UnmanagedType.LPStr)] string property, ref long oldp, ref long oldlenp, IntPtr newp, /* size_t */ long newlen);

translated = syctlbyname ("sysctl.proc_translated", ref result, ref size, IntPtr.Zero, 0);

and it's not unsafe anymore.

[monojenkins]

Build failure
✅ Build succeeded
✅ API Diff (from stable)
✅ API Diff (from PR only) (no change)
✅ Generator Diff (no change)
🔥 Test run failed 🔥

Test results

2 tests failed, 59 tests passed.

Failed tests

• mmptest/macOS/Debug: Failed (Execution failed with exit code 1)
• MTouch tests/NUnit: Failed (Execution failed with exit code 5)

[monojenkins]

Build failure
❌ Build failed or was aborted

🔥 Build failed 🔥

[monojenkins]

Build failure
✅ Build succeeded
✅ API Diff (from stable)
✅ API Diff (from PR only) (no change)
✅ Generator Diff (no change)
🔥 Test run failed 🔥

Test results

2 tests failed, 59 tests passed.

Failed tests

• mmptest/macOS/Debug: Failed (Execution failed with exit code 1)
• MTouch tests/NUnit: Failed (Execution failed with exit code 5)

[monojenkins]

Build failure
✅ Build succeeded
✅ API Diff (from stable)
✅ API Diff (from PR only) (no change)
✅ Generator Diff (no change)
🔥 Test run failed 🔥

Test results

1 tests failed, 60 tests passed.

Failed tests

• MTouch tests/NUnit: Failed (Execution failed with exit code 5)

[spouliot]

unrelated network failures are a known issue -> https://github.com/xamarin/maccore/issues/2154