[Xamarin.Android.Build.Tasks] Fix bug in the Design Time Build (#9711)

We got a bug report that a .NET 10 design-time build in VS results in
the following error:

    System.ArgumentOutOfRangeException: Positive number required.
    Parameter name: bufferSize
       at System.IO.StreamReader..ctor(Stream stream, Encoding encoding, Boolean detectEncodingFromByteOrderMarks, Int32 bufferSize, Boolean leaveOpen)
       at Xamarin.Android.Tasks.GenerateResourceCaseMap.RunTask() in /Users/runner/work/1/s/xamarin-android/src/Xamarin.Android.Build.Tasks/Tasks/GenerateResourceCaseMap.cs:line 94
       at Microsoft.Android.Build.Tasks.AndroidTask.Execute() in /Users/runner/work/1/s/xamarin-android/external/xamarin-android-tools/src/Microsoft.Android.Build.BaseTasks/AndroidTask.cs:line 25

We were passing `-1` as the `bufferSize`. While this is fine under .NET 9/10.
It seems the full .NET framework does not like it.

So, lets fix it by passing `4096`.

Author: dellis1972

src/Xamarin.Android.Build.Tasks/Tasks/GenerateResourceCaseMap.cs

@@ -91,7 +91,7 @@ public override bool RunTask ()
 							entryStream.CopyTo (ms);
 						}
 						ms.Position = 0;
-						using (var reader = new StreamReader (ms, Encoding.UTF8, detectEncodingFromByteOrderMarks: true, bufferSize: -1, leaveOpen: true)) {
+						using (var reader = new StreamReader (ms, Encoding.UTF8, detectEncodingFromByteOrderMarks: true, bufferSize: 4096, leaveOpen: true)) {
 							string line;
 							// Read each line until the end of the file
 							while ((line = reader.ReadLine()) != null) {