VS,Xcode: Add CMakeLists.txt sources without mutating targets

Rather than injecting `CMakeLists.txt` files into each target's
`SOURCES`, teach the generators to add them during generation using
dedicated code.  This avoids mutating the original targets, and avoids
polluting `$<TARGET_PROPERTY:foo,SOURCES>` with generator-specific
content.

This also avoids listing the `CMakeLists.txt` sources in the results of
`CMAKE_DEBUG_TARGET_PROPERTIES==SOURCES` so the `RunCMake.TargetSources`
test no longer needs a separate case for IDEs.

Source/cmLocalVisualStudio7Generator.h

@@ -65,7 +65,6 @@ public:
 
   virtual void ReadAndStoreExternalGUID(const std::string& name,
                                         const char* path);
-  virtual void AddCMakeListsRules();
 
 protected:
   void CreateSingleVCProj(const std::string& lname, cmGeneratorTarget* tgt);
@@ -117,10 +116,11 @@ private:
                        FCInfo& fcinfo);
   void WriteTargetVersionAttribute(std::ostream& fout, cmGeneratorTarget* gt);
 
+  class AllConfigSources;
   bool WriteGroup(const cmSourceGroup* sg, cmGeneratorTarget* target,
                   std::ostream& fout, const std::string& libName,
                   std::vector<std::string> const& configs,
-                  std::map<cmSourceFile const*, size_t> const& sourcesIndex);
+                  AllConfigSources const& sources);
 
   friend class cmLocalVisualStudio7GeneratorFCInfo;
   friend class cmLocalVisualStudio7GeneratorInternals;