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/Starfield/Starfield.cpp b/Userland/Demos/Starfield/Starfield.cpp
index ab96f3d82e..90eda0ba7e 100644
--- a/Userland/Demos/Starfield/Starfield.cpp
+++ b/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();