Use Environment.SpecialFolder.UserProfile, not SpecialFolder.Personal (#194)

Context: dotnet/runtime#68610

In Mono and .NET prior to .NET 8, the
[`System.Environment.SpecialFolder`][0]`.Personal` enum value would
refer to `$HOME` on Unix platforms.

This will be changing in .NET 8, such that
`Environment.SpecialFolder.Personal` will instead refer to
`$XDG_DOCUMENTS_DIR` (if set) or `$HOME/Documents`.  This is for
"semantic compatibility" with .NET on Windows.

Replace usage of `Environment.SpecialFolder.Personal` with
`Environment.SpecialFolder.UserProfile`, so that our code continues
to work as expected under .NET 8.

[0]: https://docs.microsoft.com/en-us/dotnet/api/system.environment.specialfolder?view=net-6.0

Author: eerhardt

src/Xamarin.Android.Tools.AndroidSdk/Jdks/MicrosoftDistJdkLocations.cs

@@ -21,7 +21,7 @@ static IEnumerable<string> GetMacOSMicrosoftDistJdkPaths ()
 			var jdks    = AppDomain.CurrentDomain.GetData ($"GetMacOSMicrosoftJdkPaths jdks override! {typeof (JdkInfo).AssemblyQualifiedName}")
 				?.ToString ();
 			if (jdks == null) {
-				var home    = Environment.GetFolderPath (Environment.SpecialFolder.Personal);
+				var home    = Environment.GetFolderPath (Environment.SpecialFolder.UserProfile);
 				jdks        = Path.Combine (home, "Library", "Developer", "Xamarin", "jdk");
 			}
 			if (!Directory.Exists (jdks))

src/Xamarin.Android.Tools.AndroidSdk/OS.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Runtime.InteropServices;
 using System.IO;
@@ -69,15 +69,15 @@ static string GetProgramFilesX86 ()
 		internal static string GetXamarinAndroidCacheDir ()
 		{
 			if (IsMac) {
-				var home = Environment.GetFolderPath (Environment.SpecialFolder.Personal);
+				var home = Environment.GetFolderPath (Environment.SpecialFolder.UserProfile);
 				return Path.Combine (home, "Library", "Caches", "Xamarin.Android");
 			} else if (IsWindows) {
 				var localAppData = Environment.GetFolderPath (Environment.SpecialFolder.LocalApplicationData);
 				return Path.Combine (localAppData, "Xamarin.Android", "Cache");
 			} else {
-				var home = Environment.GetFolderPath (Environment.SpecialFolder.Personal);
 				var xdgCacheHome = Environment.GetEnvironmentVariable ("XDG_CACHE_HOME");
 				if (string.IsNullOrEmpty (xdgCacheHome)) {
+					var home = Environment.GetFolderPath (Environment.SpecialFolder.UserProfile);
 					xdgCacheHome = Path.Combine (home, ".cache");
 				}
 				return Path.Combine (xdgCacheHome, "Xamarin.Android");

src/Xamarin.Android.Tools.AndroidSdk/Sdks/AndroidSdkUnix.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Linq;
 using System.Collections.Generic;
 using System.Diagnostics;
@@ -111,7 +111,7 @@ protected override IEnumerable<string> GetAllAvailableAndroidSdks ()
 			}
 
 			// Check some hardcoded paths for good measure
-			var macSdkPath = Path.Combine (Environment.GetFolderPath (Environment.SpecialFolder.Personal), "Library", "Android", "sdk");
+			var macSdkPath = Path.Combine (Environment.GetFolderPath (Environment.SpecialFolder.UserProfile), "Library", "Android", "sdk");
 			yield return macSdkPath;
 		}