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/Mandelbrot/Mandelbrot.cpp b/Userland/Demos/Mandelbrot/Mandelbrot.cpp
index 41a7a2cef7..c7538d2925 100644
--- a/Userland/Demos/Mandelbrot/Mandelbrot.cpp
+++ b/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"));