Merged TdsParserHelperClasses - removed per-platform files

Author: edwardneal

src/Microsoft.Data.SqlClient/netcore/src/Microsoft.Data.SqlClient.csproj

@@ -688,7 +688,6 @@
     <Compile Include="Microsoft\Data\SqlClient\TdsParser.cs" />
     <Compile Include="Microsoft\Data\SqlClient\TdsParser.NetCoreApp.cs" />
     <Compile Include="Microsoft\Data\SqlClient\TdsParser.RegisterEncoding.cs" />
-    <Compile Include="Microsoft\Data\SqlClient\TdsParserHelperClasses.NetCoreApp.cs" />
     <Compile Include="Microsoft\Data\SqlClient\TdsParserStateObject.netcore.cs" />
     <Compile Include="Microsoft\Data\SqlClient\TdsParserStateObjectManaged.cs" />
     <Compile Include="Microsoft\Data\SqlTypes\SqlTypeWorkarounds.netcore.cs" />

src/Microsoft.Data.SqlClient/netcore/src/Microsoft/Data/SqlClient/TdsParserHelperClasses.NetCoreApp.cs

@@ -718,7 +718,6 @@
     <Compile Include="Microsoft\Data\SqlClient\SqlSequentialTextReaderSmi.cs" />
     <Compile Include="Microsoft\Data\SqlClient\SqlTransaction.cs" />
     <Compile Include="Microsoft\Data\SqlClient\TdsParser.cs" />
-    <Compile Include="Microsoft\Data\SqlClient\TdsParserHelperClasses.netfx.cs" />
     <Compile Include="Microsoft\Data\SqlClient\TdsParserStateObject.netfx.cs" />
     <Compile Include="Microsoft\Data\SqlTypes\SqlFileStream.cs" />
     <Compile Include="Microsoft\Data\SqlTypes\SqlStreamChars.cs" />