Revert "Replace Shell sans-serif-medium magic string on Android (#15698)" (#15705)

This reverts commit 51d8c70.

Author: jfversluis

Xamarin.Forms.Core/Shell/BaseShellItem.cs

@@ -453,6 +453,7 @@ internal static DataTemplate CreateDefaultFlyoutItemCell(string textBinding, str
 				{
 					defaultLabelClass.Setters.Add(new Setter { Property = Label.FontSizeProperty, Value = 14 });
 					defaultLabelClass.Setters.Add(new Setter { Property = Label.TextColorProperty, Value = Color.Black.MultiplyAlpha(0.87) });
+					defaultLabelClass.Setters.Add(new Setter { Property = Label.FontFamilyProperty, Value = "sans-serif-medium" });
 					defaultLabelClass.Setters.Add(new Setter { Property = Label.MarginProperty, Value = new Thickness(20, 0, 0, 0) });
 				}
 				else if (Device.RuntimePlatform == Device.iOS)

Xamarin.Forms.Platform.Android/Renderers/BottomNavigationViewUtils.cs

@@ -173,7 +173,7 @@ void clickCallback(object s, EventArgs e)
 
 					using (var text = new TextView(context))
 					{
-						text.SetTypeface(Typeface.SansSerif, TypefaceStyle.Normal);
+						text.SetTypeface(Typeface.Create("sans-serif-medium", TypefaceStyle.Normal), TypefaceStyle.Normal);
 						text.SetTextColor(AColor.Black);
 						text.Text = shellContent.title;
 						lp = new LinearLayout.LayoutParams(0, LP.WrapContent)

Xamarin.Forms.Platform.Android/Renderers/ShellItemRenderer.cs

@@ -3,7 +3,6 @@
 using System.Collections.Specialized;
 using System.ComponentModel;
 using Android.Content;
-using Android.Graphics;
 using Android.Graphics.Drawables;
 using Android.OS;
 using Android.Views;
@@ -217,7 +216,7 @@ void clickCallback(object s, EventArgs e)
 
 					using (var text = new TextView(Context))
 					{
-						text.Typeface = Typeface.SansSerif;
+						text.Typeface = "sans-serif-medium".ToTypeFace();
 						text.SetTextColor(AColor.Black);
 						text.Text = shellContent.Title;
 						lp = new LinearLayout.LayoutParams(0, LP.WrapContent)