CMake: Use source_groups to represent the source tree

* It let ide's (like vs) display the source tree.
* Disabled by default.
* Soft requirement is cmake >= 2.8.12 .
* Offers 2 modes: flat & hierarchical.
* For detailed description see #14471
* Thanks @click for help and advises.
* Closes #14471

src/server/scripts/CMakeLists.txt

@@ -146,6 +146,8 @@ include_directories(
   ${VALGRIND_INCLUDE_DIR}
 )
 
+GroupSources(${CMAKE_CURRENT_SOURCE_DIR})
+
 add_library(scripts STATIC
   ${scripts_STAT_SRCS}
   ${scripts_STAT_PCH_SRC}