Add an #[embedded_css_module] macro for non dx-serve/dx-bundle enviorments.

[rydb]

Feature Request

the static type checking that #[css_module] macro has is very useful, but it's locked behind dx serve/dx bundle. If you are using dioxus in an environment where you don't have access to those (bevy dioxus native), (side-stepping the bundler for direct executable files), you can't use it. Asset! does work for these environments, but you lose #[css_module]'s type checking.

If there were a #[embedded_css_module], it would allow keeping css classes type checked while still being able to work in non dx serve/dx bundle-able environments.