Provide type checking support for HTML attribute values in `rsx` macro about dioxus HOT 2 OPEN

I have some concerns about the binary size impact of typed HTML in WASM. One of the largest pieces of dioxus-web today is just converting a typed enum key in events to and from a string. Each part of typed HTML would need similar logic which may have a large binary size.

from dioxus.

For enums, we could actually expand the values to const associated generics with &'static str values which wouldn't have a binary size impact.

In:

input { 
     r#type: Type::Email,
}

Type could be a struct like this:

struct Type;
impl Type {
    pub const Email: &'static = "email";
}

https://github.com/microsoft/vscode-custom-data has type data vscode uses for autocomplete. We could use it in a build script to generate const associated types for attributes in dioxus. (Could be useful to steal out some of the serde logic from https://github.com/ealmloff/html-parser/blob/main/build.rs)

This would also make autocomplete for values much nicer.

from dioxus.