PchManager: Split pch tasks in project and system pch tasks

Like you can see in the task numbers this patch is touching many different
areas. So I will only touch the main parts. It is using a clang action
instead of an extra process which will be enabling the handling of
generated files in PCHs. The flags from the project part are now not
anymore transformed in a command line but they are saved in the container
semantically aware so that they can later be merged. Most of this patch is
simply polishing of other patches.

Task-number: QTCREATORBUG-21346
Task-number: QTCREATORBUG-21380
Task-number: QTCREATORBUG-21382
Task-number: QTCREATORBUG-21383
Task-number: QTCREATORBUG-21693
Task-number: QTCREATORBUG-21778
Change-Id: I9b0c02d8149b554254e819448fbc61eeaa5b7494
Reviewed-by: Ivan Donchevskii <ivan.donchevskii@qt.io>

src/tools/clangrefactoringbackend/source/clangtool.cpp

@@ -50,9 +50,9 @@ void ClangTool::addFile(std::string &&directory,
                         std::vector<std::string> &&commandLine)
 {
     m_fileContents.emplace_back(toNativePath(std::move(directory)),
-                              std::move(fileName),
-                              std::move(content),
-                              std::move(commandLine));
+                                std::move(fileName),
+                                std::move(content),
+                                std::move(commandLine));
 
     const auto &fileContent = m_fileContents.back();
 
@@ -140,4 +140,13 @@ clang::tooling::ClangTool ClangTool::createTool() const
     return tool;
 }
 
+clang::tooling::ClangTool ClangTool::createOutputTool() const
+{
+    clang::tooling::ClangTool tool = createTool();
+
+    tool.clearArgumentsAdjusters();
+
+    return tool;
+}
+
 } // namespace ClangBackEnd