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/glsleditor/glsleditor.cpp

@@ -319,7 +319,7 @@ GlslEditorFactory::GlslEditorFactory()
 
     setDocumentCreator([]() { return new TextDocument(Constants::C_GLSLEDITOR_ID); });
     setEditorWidgetCreator([]() { return new GlslEditorWidget; });
-    setIndenterCreator([]() { return new GlslIndenter; });
+    setIndenterCreator([](QTextDocument *doc) { return new GlslIndenter(doc); });
     setSyntaxHighlighterCreator([]() { return new GlslHighlighter; });
     setCommentDefinition(Utils::CommentDefinition::CppStyle);
     setCompletionAssistProvider(new GlslCompletionAssistProvider);