Don't import Microsoft.WinFX.targets for sdk style projects (dotnet#5200

)

* Conditional import on microsoft.winfx.targets

* Escape hatch for logging ALL task inputs rather than truncating them

* Short circuiting the condition to prevent a file check if the property is false.

* Changed name to be more explicit

* Revert "Escape hatch for logging ALL task inputs rather than truncating them"

This reverts commit 07a6146.

src/Tasks/Microsoft.WinFx.targets

@@ -9,6 +9,6 @@
         the shim will internally simply redirect to the real copy of the targets file in the .NET Framework. 
    -->
 
-   <Import Project="$(MSBuildFrameworkToolsPath)\Microsoft.WinFx.targets" Condition="Exists('$(MSBuildFrameworkToolsPath)\Microsoft.WinFx.targets')" />
+   <Import Project="$(MSBuildFrameworkToolsPath)\Microsoft.WinFx.targets" Condition="'$(ImportFrameworkWinFXTargets)' != 'false' and Exists('$(MSBuildFrameworkToolsPath)\Microsoft.WinFx.targets')" />
 
 </Project>