LibGUI+Everywhere: Use fallible Window::set_main_widget() everywhere :^)

Rip that bandaid off!

This does the following, in one big, awkward jump:
- Replace all uses of `set_main_widget<Foo>()` with the `try` version.
- Remove `set_main_widget<Foo>()`.
- Rename the `try` version to just be `set_main_widget` because it's now
  the only one.

The majority of places that call `set_main_widget<Foo>()` are inside
constructors, so this unfortunately gives us a big batch of new
`release_value_but_fixme_should_propagate_errors()` calls.

Userland/Demos/CatDog/main.cpp

@@ -62,7 +62,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     advice_window->set_has_alpha_channel(true);
     advice_window->set_alpha_hit_threshold(1.0f);
 
-    auto advice_widget = TRY(advice_window->try_set_main_widget<SpeechBubble>(catdog_widget));
+    auto advice_widget = TRY(advice_window->set_main_widget<SpeechBubble>(catdog_widget));
     (void)TRY(advice_widget->try_set_layout<GUI::VerticalBoxLayout>());
     advice_widget->layout()->set_spacing(0);
 

Userland/Demos/Eyes/main.cpp

@@ -97,7 +97,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     })));
     TRY(help_menu->try_add_action(GUI::CommonActions::make_about_action("Eyes Demo", app_icon, window)));
 
-    auto eyes_widget = TRY(window->try_set_main_widget<EyesWidget>(num_eyes, full_rows, extra_columns));
+    auto eyes_widget = TRY(window->set_main_widget<EyesWidget>(num_eyes, full_rows, extra_columns));
     eyes_widget->on_context_menu_request = [&](auto& event) {
         file_menu->popup(event.screen_position());
     };

Userland/Demos/GradientScreensaver/GradientScreensaver.cpp

@@ -97,7 +97,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     auto window = TRY(Desktop::Screensaver::create_window("Screensaver"sv, "app-screensaver"sv));
 
-    auto screensaver_window = TRY(window->try_set_main_widget<Screensaver>(64, 48, 10000));
+    auto screensaver_window = TRY(window->set_main_widget<Screensaver>(64, 48, 10000));
     screensaver_window->set_fill_with_background_color(false);
     screensaver_window->set_override_cursor(Gfx::StandardCursor::Hidden);
     screensaver_window->update();

Userland/Demos/LibGfxDemo/main.cpp

@@ -200,7 +200,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     auto app_icon = TRY(GUI::Icon::try_create_default_icon("app-libgfx-demo"sv));
     window->set_icon(app_icon.bitmap_for_size(16));
-    (void)TRY(window->try_set_main_widget<Canvas>());
+    (void)TRY(window->set_main_widget<Canvas>());
     window->show();
 
     return app->exec();

Userland/Demos/LibGfxScaleDemo/main.cpp

@@ -121,7 +121,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     auto app_icon = TRY(GUI::Icon::try_create_default_icon("app-libgfx-demo"sv));
     window->set_icon(app_icon.bitmap_for_size(16));
-    (void)TRY(window->try_set_main_widget<Canvas>());
+    (void)TRY(window->set_main_widget<Canvas>());
     window->show();
 
     return app->exec();

Userland/Demos/Mandelbrot/Mandelbrot.cpp

@@ -413,7 +413,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     window->set_obey_widget_min_size(false);
     window->set_minimum_size(320, 240);
     window->resize(window->minimum_size() * 2);
-    auto mandelbrot = TRY(window->try_set_main_widget<Mandelbrot>());
+    auto mandelbrot = TRY(window->set_main_widget<Mandelbrot>());
 
     auto file_menu = TRY(window->try_add_menu("&File"));
 

Userland/Demos/ModelGallery/main.cpp

@@ -28,7 +28,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     window->set_title("Model Gallery");
     window->set_icon(app_icon.bitmap_for_size(16));
     window->resize(430, 480);
-    (void)TRY(window->try_set_main_widget<GalleryWidget>());
+    (void)TRY(window->set_main_widget<GalleryWidget>());
 
     window->show();
     return app->exec();

Userland/Demos/Screensaver/main.cpp

@@ -86,7 +86,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     TRY(help_menu->try_add_action(GUI::CommonActions::make_command_palette_action(window)));
     TRY(help_menu->try_add_action(GUI::CommonActions::make_about_action("Screensaver", app_icon, window)));
 
-    auto main_widget = TRY(window->try_set_main_widget<GUI::Widget>());
+    auto main_widget = TRY(window->set_main_widget<GUI::Widget>());
     main_widget->set_fill_with_background_color(true);
     main_widget->set_layout<GUI::VerticalBoxLayout>();
 

Userland/Demos/Starfield/Starfield.cpp

@@ -167,7 +167,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     auto window = TRY(Desktop::Screensaver::create_window("Starfield"sv, "app-starfield"sv));
 
-    auto starfield_window = TRY(window->try_set_main_widget<Starfield>(refresh_rate));
+    auto starfield_window = TRY(window->set_main_widget<Starfield>(refresh_rate));
     starfield_window->set_fill_with_background_color(false);
     starfield_window->set_override_cursor(Gfx::StandardCursor::Hidden);
     starfield_window->update();

Userland/Demos/Tubes/main.cpp

@@ -30,7 +30,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     auto window = TRY(Desktop::Screensaver::create_window("Tubes"sv, "app-tubes"sv));
     window->update();
 
-    auto tubes_widget = TRY(window->try_set_main_widget<Tubes>(refresh_rate));
+    auto tubes_widget = TRY(window->set_main_widget<Tubes>(refresh_rate));
     tubes_widget->set_fill_with_background_color(false);
     tubes_widget->set_override_cursor(Gfx::StandardCursor::Hidden);
     window->show();

Userland/Demos/WidgetGallery/main.cpp

@@ -28,7 +28,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     window->resize(430, 480);
     window->set_title("Widget Gallery");
     window->set_icon(app_icon.bitmap_for_size(16));
-    (void)TRY(window->try_set_main_widget<GalleryWidget>());
+    (void)TRY(window->set_main_widget<GalleryWidget>());
     window->show();
 
     return app->exec();