Updated cmake to better organize folders and options.

This adds solution folders that properly group gtest/glslang/hlsl.
This also marks gtest options as advanced so they don't show up
in cmake-gui by default.

hlsl/CMakeLists.txt

@@ -14,6 +14,7 @@ set(HEADERS
     hlslGrammar.h)
 
 add_library(HLSL STATIC ${SOURCES} ${HEADERS})
+set_property(TARGET HLSL PROPERTY FOLDER hlsl)
 
 if(WIN32)
     source_group("Source" FILES ${SOURCES} ${HEADERS})