ClangFormat: Refactor indenter to allow ClangFormat unit-tests

We do not build texteditor files in unit-tests so some tricks
were required to make ClangFormatIndenter available.

First simple unit-test proofs it builds and runs.

Change-Id: I81d5ea099bd27fd1c1ed8b5b7877299dcc62a67f
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@qt.io>

src/plugins/pythoneditor/pythoneditor.cpp

@@ -54,7 +54,7 @@ PythonEditorFactory::PythonEditorFactory()
                             | TextEditorActionHandler::FollowSymbolUnderCursor);
 
     setDocumentCreator([] { return new TextDocument(Constants::C_PYTHONEDITOR_ID); });
-    setIndenterCreator([] { return new PythonIndenter; });
+    setIndenterCreator([](QTextDocument *doc) { return new PythonIndenter(doc); });
     setSyntaxHighlighterCreator([] { return new PythonHighlighter; });
     setCommentDefinition(Utils::CommentDefinition::HashStyle);
     setParenthesesMatchingEnabled(true);