LibGUI+Userland: Make Dialog::ExecResult an enum class

Author: https://github.com/AtkinsSJ
Commit: cdffe556c8
Pull-request: https://github.com/SerenityOS/serenity/pull/14021
Reviewed-by: https://github.com/linusg ✅

Userland/Applications/PixelPaint/CreateNewLayerDialog.cpp

@@ -51,12 +51,12 @@ CreateNewLayerDialog::CreateNewLayerDialog(Gfx::IntSize const& suggested_size, G
 
     auto& ok_button = button_container.add<GUI::Button>("OK");
     ok_button.on_click = [this](auto) {
-        done(ExecOK);
+        done(ExecResult::OK);
     };
 
     auto& cancel_button = button_container.add<GUI::Button>("Cancel");
     cancel_button.on_click = [this](auto) {
-        done(ExecCancel);
+        done(ExecResult::Cancel);
     };
 
     width_spinbox.on_change = [this](int value) {
@@ -68,7 +68,7 @@ CreateNewLayerDialog::CreateNewLayerDialog(Gfx::IntSize const& suggested_size, G
     };
 
     m_name_textbox->on_return_pressed = [this] {
-        done(ExecOK);
+        done(ExecResult::OK);
     };
 
     width_spinbox.set_range(1, 16384);