Rename Rune to UnicodeScalar

Author: GrabYourPitchforks

src/System.Private.CoreLib/shared/System.Private.CoreLib.Shared.projitems

@@ -599,12 +599,12 @@
     <Compile Include="$(MSBuildThisFileDirectory)System\Text\EncodingProvider.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Text\Latin1Encoding.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Text\NormalizationForm.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)System\Text\Rune.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Text\StringBuilder.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Text\StringBuilder.Debug.cs" Condition="'$(Configuration)' == 'Debug'" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Text\UnicodeDebug.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Text\UnicodeEncoding.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Text\UnicodeUtility.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Text\UnicodeScalar.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Text\Utf16Utility.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Text\UTF32Encoding.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Text\UTF7Encoding.cs" />