VS: Use MSBuild project for ALL_BUILD
Previously, VS 10 generator generated C++ project for target ALL_BUILD. This PR switches the project for that target to be a plain and simple MSBuild project which defines other projects as the target to build, clean, or rebuild.
This change will allow CMake to build C++ and C# projects in one solution without taking any dependency on .Net SDK or C++ toolset.
Edited by Brad King