LibGUI: Give some widgets a reasonable default fixed height

Instead of hard-coding 22 in random places, just make the following
widgets have a fixed height of 22 by default: Button, CheckBox,
ColorInput, ComboBox, RadioButton, SpinBox, TextBox.

In the future we can make this relative to the current font size,
but for now at least this centralizes the setting a bit better.

Demos/DynamicObject/main.cpp

@@ -68,7 +68,6 @@ int main([[maybe_unused]] int argc, [[maybe_unused]] char** argv, [[maybe_unused
 
     auto& button = main_widget.add<GUI::Button>();
     button.set_text("Good-bye");
-    button.set_fixed_height(20);
     button.on_click = [&](auto) {
         app->quit();
     };