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/texteditor/codeassist/genericproposal.h

@@ -27,6 +27,7 @@
 
 #include "iassistproposal.h"
 
+#include <texteditor/quickfix.h>
 
 namespace TextEditor {
 
@@ -38,8 +39,12 @@ class TEXTEDITOR_EXPORT GenericProposal : public IAssistProposal
 public:
     GenericProposal(int cursorPos, GenericProposalModel *model);
     GenericProposal(int cursorPos, const QList<AssistProposalItemInterface *> &items);
+
     ~GenericProposal();
 
+    static GenericProposal *createProposal(const AssistInterface *interface,
+                                           const QuickFixOperations &quickFixes);
+
     bool hasItemsToPropose(const QString &prefix, AssistReason reason) const override;
     IAssistProposalModel *model() const override;
     IAssistProposalWidget *createWidget() const override;