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/clangtools/clangfixitsrefactoringchanges.h

@@ -25,6 +25,8 @@
 
 #pragma once
 
+#include <texteditor/indenter.h>
+
 #include <utils/changeset.h>
 #include <utils/textfileformat.h>
 
@@ -32,13 +34,6 @@
 #include <QTextDocument>
 #include <QVector>
 
-namespace TextEditor {
-class Indenter;
-class Replacement;
-using Replacements = std::vector<Replacement>;
-class TabSettings;
-}
-
 namespace ClangTools {
 namespace Internal {