ClangFormat: Start to use new file management

- Indenter uses .clang-format file from a dir of
editing file or from a parent dir. If there is no
such file then indenter starts to use file from a dir
with the name current CodeStyle settings.
- Test fixed

ToDo: Add file absentness processing in case of import

Change-Id: If09ef0c598899856b948c214e524bcfd5dad76e2
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/clangformat/clangformatutils.h

@@ -34,6 +34,7 @@
 
 #include <fstream>
 
+namespace TextEditor { class ICodeStylePreferences; }
 namespace ClangFormat {
 
 // Creates the style for the current project or the global style if needed.
@@ -55,4 +56,6 @@ void saveStyleToFile(clang::format::FormatStyle style, Utils::FilePath filePath)
 
 void addQtcStatementMacros(clang::format::FormatStyle &style);
 clang::format::FormatStyle qtcStyle();
+
+Utils::FilePath filePathToCurrentSettings(const TextEditor::ICodeStylePreferences *codeStyle);
 }