Copilot: add copilot suggestion tooltips

These tooltips allow to switch the currently visible suggestion as well
as applying it using
the mouse.

Change-Id: I30b9a76ae57c66887f4e1b1311e1a7248ed0f194
Reviewed-by: Marcus Tillmanns <marcus.tillmanns@qt.io>

src/plugins/texteditor/basehoverhandler.h

@@ -39,7 +39,8 @@ protected:
         Priority_None = 0,
         Priority_Tooltip = 5,
         Priority_Help = 10,
-        Priority_Diagnostic = 20
+        Priority_Diagnostic = 20,
+        Priority_Suggestion = 40
     };
     void setPriority(int priority);
     int priority() const;