logic: Added PCH support to CDB source groups (issue #311)

* added PCH Flags list and checkbox to reuse compiler flags and cdb flags to source group setup
* added UI tests for C++ and CDB source groups

testing/project_setup/cpp_empty_pch/data/src/main.cpp

@@ -0,0 +1,7 @@
+#include "pch.h"
+
+void test()
+{
+	Foo foo;
+	Bar bar;
+}