TextEditor: Dissolve QuickFixAssistProcessor

... into QuickFixAssistProcessor and QmlJSQuickFixAssistProcessor,
by essentially duplicating the class, but moving the actual work to
a new a GenericProposal::createProposal(...QuickFixOperations...)

Less indirection, and less code in total.

Change-Id: I2f8cba970bf587c9cbf04321269a60ed51bfae2a
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/qmljseditor/qmljsquickfix.cpp

@@ -78,11 +78,4 @@ void QmlJSQuickFixFactory::matchingOperations(const QuickFixInterface &interface
     match(interface.staticCast<const QmlJSQuickFixAssistInterface>(), result);
 }
 
-QList<TextEditor::QuickFixFactory *> QmlJSQuickFixFactory::qmlJSQuickFixFactories()
-{
-    return Utils::filtered(QuickFixFactory::allQuickFixFactories(), [](QuickFixFactory *f) {
-        return qobject_cast<QmlJSQuickFixFactory *>(f) != nullptr;
-    });
-}
-
 } // namespace QmlJSEditor