Feat: massive changes to definition of components

This change switches back to the original `ctx<props>` syntax for
commponents. This lets lifetime elision to remove the need to match
exactly which lifetime (props or ctx) gets  carried to the output. As
such, `Props` is currently required to be static. It *is* possible to
loosen this restriction, and will be done in the future, though only
through adding metadata about the props through the Props derive
macro. Implementing the IS_STATIC trait is unsafe, so the derive macro
will do it through some heuristics.

For now, this unlocks sharing vnodes from parents to children, enabling
pass-thru components, fragments, portals, etc.

examples/external_updates.rs

@@ -21,12 +21,12 @@ struct RootProps {
     navigator: Receiver<&'static str>,
 }
 
-fn App(ctx: Context, props: &RootProps) -> DomTree {
+fn App(ctx: Context, props: &RootProps) -> VNode {
     let router = use_router(&ctx, |router| {});
 
     let navigator = use_history(&ctx);
 
-    use_receiver(&ctx, || props.recv.clone(), |to| navigator.navigate(to));
+    use_receiver(&ctx, || ctx.recv.clone(), |to| navigator.navigate(to));
 
     ctx.render(rsx! {
         div {