Add non-exhaustive to the derived props in #[component]

[ealmloff]

Currently it is a breaking change to add an optional field to a public component with props derived with the #[component] macro even though it isn't breaking for usage within rsx. This PR adds non_exhaustive to the derived props so it isn't breaking in future releases.

Changing this component:

#[component]
pub fn Button() -> Element {...}

To this:

#[component]
pub fn Button(color: Option<String>) -> Element {...}

Is breaking because there is a public generated ButtonProps with public fields that could be constructed manually