fix few Filesystem tests on FreeBSD (#65059)

* fix few FileSystem tests on FreeBSD

* fix MoveDirectory_FailToMoveLowerCaseDirectoryWhenUpperCaseDirectoryExists

* feedback from review

Author: wfurt

src/libraries/Common/tests/TestUtilities/System/PlatformDetection.cs

@@ -44,6 +44,7 @@ public static partial class PlatformDetection
         public static bool IsAppleMobile => IsMacCatalyst || IsiOS || IstvOS;
         public static bool IsNotAppleMobile => !IsAppleMobile;
         public static bool IsNotNetFramework => !IsNetFramework;
+        public static bool IsBsdLike => IsOSXLike || IsFreeBSD || IsNetBSD;
 
         public static bool IsArmProcess => RuntimeInformation.ProcessArchitecture == Architecture.Arm;
         public static bool IsNotArmProcess => !IsArmProcess;

src/libraries/System.IO.FileSystem/tests/Directory/Move.cs

@@ -343,7 +343,7 @@ public void MoveDirectory_NoOpWhenMovingDirectoryWithUpperCaseToOtherDirectoryWi
         }
 
         [Fact]
-        [PlatformSpecific(TestPlatforms.Windows | TestPlatforms.OSX | TestPlatforms.FreeBSD | TestPlatforms.NetBSD)]
+        [PlatformSpecific(TestPlatforms.Windows | TestPlatforms.OSX)]
         public void MoveDirectory_FailToMoveLowerCaseDirectoryWhenUpperCaseDirectoryExists()
         {
             Directory.CreateDirectory($"{TestDirectory}/bar/FOO");

src/libraries/System.IO.FileSystem/tests/FileStream/ctor_options.Unix.cs

@@ -15,8 +15,8 @@ private static long GetAllocatedSize(FileStream fileStream)
             using var px = Process.Start(new ProcessStartInfo
             {
                 FileName = "stat",
-                ArgumentList = { isOSX ? "-f"    : "-c",
-                                 isOSX ? "%b %k" : "%b %B",
+                ArgumentList = { PlatformDetection.IsBsdLike ? "-f"    : "-c",
+                                 PlatformDetection.IsBsdLike ? "%b %k" : "%b %B",
                                  fileStream.Name },
                 RedirectStandardOutput = true
             });