logic: indexer command refactoring

* moved SystemHeaderSearchPaths and FramewordSeearchPaths of indexer cxx indexer commands to CompilerFlags section
* added SourceGroupTestSuite to test indexer command generation of all source groups
* removed "compile_commands.json" from gitignore, because a resource file for the tests has this name

src/test/CxxParserTestSuite.h

@@ -4124,8 +4124,6 @@ public:
 			excludeFilters,
 			includeFilters,
 			workingDirectory,
-			std::vector<FilePath>(),
-			std::vector<FilePath>(),
 			std::vector<std::wstring> { L"--target=x86_64-pc-windows-msvc", L"-std=c++1z", sourceFilePath.wstr() }
 		);