EditorManager: Small API clean-up

- Move private enum to private header
- Add missing parameter to openEditorAtSearchResult
- Remove convenience singular close* methods, we have {} nowadays

Change-Id: Ic5b6d831a9f506ffee09b89b3358874433d62998
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/debugger/sourceagent.cpp

@@ -75,7 +75,7 @@ SourceAgentPrivate::SourceAgentPrivate()
 SourceAgentPrivate::~SourceAgentPrivate()
 {
     if (editor)
-        EditorManager::closeDocument(editor->document());
+        EditorManager::closeDocuments({editor->document()});
     editor = nullptr;
     delete locationMark;
 }