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.

1 files changed, 1 insertions, 1 deletions

diff --git a/Userland/Demos/Tubes/main.cpp b/Userland/Demos/Tubes/main.cpp
index 66d1fc7393..b77862305f 100644
--- a/Userland/Demos/Tubes/main.cpp
+++ b/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();