Fix rsx autocomplete and diagnostics in the root; provide better completions after attributes are finished (#2656)

* fix rsx autocomplete and diagnostics in the root; provide better completions after attributes are finished

* clean up pr to use internal child parsing

* Fix peek_lowercase name

* fix comma diagnostics in the root

* Fix parsing components with a path

* remove simple routes trailing comma

* Fix incomplete_root_elements test

* Remove trailing commas from root body node in tests

---------

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

packages/core/tests/create_fragments.rs

@@ -77,7 +77,7 @@ fn fragments_across_components() {
 
     fn demo_child() -> Element {
         let world = "world";
-        rsx! { "hellO!", {world} }
+        rsx! { "hellO!" {world} }
     }
 
     assert_eq!(

packages/core/tests/create_passthru.rs

@@ -81,7 +81,7 @@ fn dynamic_node_as_root() {
     fn app() -> Element {
         let a = 123;
         let b = 456;
-        rsx! { "{a}", "{b}" }
+        rsx! { "{a}" "{b}" }
     }
 
     let mut dom = VirtualDom::new(app);