Move the document trait into a separate crate (#3035)

* add a default head method through eval
* remove the old document trait
* implement document for each platform
* pull out document into a dedicated crate to cut down on shared dependencies
---------

Co-authored-by: Jonathan Kelley <jkelleyrtp@gmail.com>

examples/crm.rs

@@ -20,13 +20,13 @@ fn main() {
         }))
         .launch(|| {
             rsx! {
-                head::Link {
+                document::Link {
                     rel: "stylesheet",
                     href: asset!("https://unpkg.com/purecss@2.0.6/build/pure-min.css"), 
                     integrity: "sha384-Uu6IeWbM+gzNVXJcM9XV3SohHtmWE+3VGi496jvgX1jyvDTXfdK+rfZc8C1Aehk5",
                     crossorigin: "anonymous"
                 }
-                head::Link { rel: "stylesheet", href: asset!("./examples/assets/crm.css") }
+                document::Link { rel: "stylesheet", href: asset!("./examples/assets/crm.css") }
                 h1 { "Dioxus CRM Example" }
                 Router::<Route> {}
             }