[essentials] ensure WebUtils.ParseQueryString captures fragment param…

…eters (#15662)

### Description of Change

Makes `WebUtils.ParseQueryString` extract parameters from both
`Uri.Query` and `Uri.Fragment`, resolving a regression from net8p4 to
net8p5.

### Issues Fixed

Fixes #15661

src/Essentials/src/Types/Shared/WebUtils.shared.cs

@@ -6,21 +6,31 @@ namespace Microsoft.Maui.ApplicationModel
 {
 	static class WebUtils
 	{
-		// The following method is a port of the logic found in https://source.dot.net/#Microsoft.AspNetCore.WebUtilities/src/Shared/QueryStringEnumerable.cs
-		// but refactored such that it:
-		//
-		// 1. avoids the IEnumerable overhead that isn't needed (the ASP.NET logic was clearly designed that way to offer a public API whereas we don't need that)
-		// 2. avoids the use of unsafe code
 		internal static IDictionary<string, string> ParseQueryString(Uri uri)
 		{
 			var parameters = new Dictionary<string, string>(StringComparer.Ordinal);
 
-			if (uri == null || string.IsNullOrEmpty(uri.Query))
+			if (uri == null)
 				return parameters;
 
 			// Note: Uri.Query starts with a '?'
-			var query = uri.Query.AsSpan(1);
+			if (!string.IsNullOrEmpty(uri.Query))
+				UnpackParameters(uri.Query.AsSpan(1), parameters);
+
+			// Note: Uri.Fragment starts with a '#'
+			if (!string.IsNullOrEmpty(uri.Fragment))
+				UnpackParameters(uri.Fragment.AsSpan(1), parameters);
+
+			return parameters;
+		}
 
+		// The following method is a port of the logic found in https://source.dot.net/#Microsoft.AspNetCore.WebUtilities/src/Shared/QueryStringEnumerable.cs
+		// but refactored such that it:
+		//
+		// 1. avoids the IEnumerable overhead that isn't needed (the ASP.NET logic was clearly designed that way to offer a public API whereas we don't need that)
+		// 2. avoids the use of unsafe code
+		static void UnpackParameters(ReadOnlySpan<char> query, Dictionary<string, string> parameters)
+		{
 			while (!query.IsEmpty)
 			{
 				int delimeterIndex = query.IndexOf('&');
@@ -66,8 +76,6 @@ internal static IDictionary<string, string> ParseQueryString(Uri uri)
 					parameters[name] = Uri.UnescapeDataString(value);
 				}
 			}
-
-			return parameters;
 		}
 
 		internal static Uri EscapeUri(Uri uri)