Copilot: Take advantage of IOptionPage::setWidgetCreator()

Less boilerplate for the implementation add user code access to
IOptionPage::{apply,finish} is planned to be removed.

Change-Id: I03bbde071fdf673bee0568baa9ae9fab8d816590
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/copilot/copilotoptionspage.cpp

@@ -17,11 +17,10 @@ using namespace LanguageClient;
 
 namespace Copilot {
 
-class CopilotOptionsPageWidget : public QWidget
+class CopilotOptionsPageWidget : public Core::IOptionsPageWidget
 {
 public:
-    CopilotOptionsPageWidget(QWidget *parent = nullptr)
-        : QWidget(parent)
+    CopilotOptionsPageWidget()
     {
         using namespace Layouting;
 
@@ -73,6 +72,12 @@ file from the Copilot neovim plugin.
                 updateAuthWidget);
         updateAuthWidget();
     }
+
+    void apply() final
+    {
+        CopilotSettings::instance().apply();
+        CopilotSettings::instance().writeSettings(Core::ICore::settings());
+    }
 };
 
 CopilotOptionsPage::CopilotOptionsPage()
@@ -82,25 +87,9 @@ CopilotOptionsPage::CopilotOptionsPage()
     setCategory("ZY.Copilot");
     setDisplayCategory("Copilot");
     setCategoryIconPath(":/copilot/images/settingscategory_copilot.png");
+    setWidgetCreator([] { return new CopilotOptionsPageWidget; });
 }
 
-CopilotOptionsPage::~CopilotOptionsPage() {}
-
-void CopilotOptionsPage::init() {}
-
-QWidget *CopilotOptionsPage::widget()
-{
-    return new CopilotOptionsPageWidget();
-}
-
-void CopilotOptionsPage::apply()
-{
-    CopilotSettings::instance().apply();
-    CopilotSettings::instance().writeSettings(Core::ICore::settings());
-}
-
-void CopilotOptionsPage::finish() {}
-
 CopilotOptionsPage &CopilotOptionsPage::instance()
 {
     static CopilotOptionsPage settingsPage;

src/plugins/copilot/copilotoptionspage.h

@@ -11,15 +11,8 @@ class CopilotOptionsPage : public Core::IOptionsPage
 {
 public:
     CopilotOptionsPage();
-    ~CopilotOptionsPage() override;
 
     static CopilotOptionsPage &instance();
-
-    void init();
-
-    QWidget *widget() override;
-    void apply() override;
-    void finish() override;
 };
 
-} // namespace Copilot
+} // Copilot

src/plugins/copilot/copilotplugin.cpp

@@ -50,7 +50,7 @@ void CopilotPlugin::initialize()
 
 void CopilotPlugin::extensionsInitialized()
 {
-    CopilotOptionsPage::instance().init();
+    (void)CopilotOptionsPage::instance();
 }
 
 void CopilotPlugin::restartClient()

src/plugins/copilot/copilotplugin.h

@@ -9,8 +9,6 @@
 
 #include <QPointer>
 
-namespace TextEditor { class TextEditorWidget; }
-
 namespace Copilot {
 namespace Internal {