feat: implement type magic to allow strings, format args, and other types directly in rsx (#550)

* feat: implement type magic

* chore: undo example

* fix: let tests pass

* chore: add generic to allow any nesting of iterators

* Chore: remove comments

* chore: update rsx usage

* chore: use cleaner version of generic IntoVnode

* chore: don't derive default for lfietimed thing

* chore: remove latent comment

* fix: accept a third parameter

examples/rsx_usage.rs

@@ -203,8 +203,8 @@ fn app(cx: Scope) -> Element {
             self::lowercase_helper {}
 
             // helper functions
-            // Single values must be wrapped in braces or `Some` to satisfy `IntoIterator`
-            [helper(&cx, "hello world!")]
+            // Anything that implements IntoVnode can be dropped directly into Rsx
+            helper(&cx, "hello world!")
         }
     })
 }