Subtree memorization / reactive templates (#488)

This commit adds subtree memoization to Dioxus.

Subtree memoization is basically a compile-time step that drastically 
reduces the amount of work the diffing engine needs to do at runtime by
extracting non-changing nodes out into a static "template." Templates 
are then understood by the various renderers in the ecosystem as a 
faster way of rendering the same items. 

For example, in the web, templates are simply a set of DOM Nodes created 
once and then cloned later. This is the same pattern frameworks like Lithtml
and SolidJS use to achieve near-perfect performance. 

Subtree memoization adds an additional level of complexity to Dioxus. The RSX
macro needs to be much smarter to identify changing/nonchanging nodes and
generate a mapping between the Template and its runtime counterparts.

This commit represents a working starter point for this work, adding support 
for templates for the web, desktop, liveview, ssr, and native-core renderers.
In the future we will try to shrink code generation, generally improve 
performance, and simplify our implementation.

packages/interpreter/src/bindings.rs

@@ -73,4 +73,44 @@ extern "C" {
 
     #[wasm_bindgen(method)]
     pub fn RemoveAttribute(this: &Interpreter, root: u64, field: &str, ns: Option<&str>);
+
+    #[wasm_bindgen(method)]
+    pub fn CreateTemplateRef(this: &Interpreter, id: u64, template_id: u64);
+
+    #[wasm_bindgen(method)]
+    pub fn CreateTemplate(this: &Interpreter, id: u64);
+
+    #[wasm_bindgen(method)]
+    pub fn FinishTemplate(this: &Interpreter, len: u32);
+
+    #[wasm_bindgen(method)]
+    pub fn EnterTemplateRef(this: &Interpreter, id: u64);
+
+    #[wasm_bindgen(method)]
+    pub fn ExitTemplateRef(this: &Interpreter);
+
+    #[wasm_bindgen(method)]
+    pub fn CreateElementTemplate(
+        this: &Interpreter,
+        tag: &str,
+        root: u64,
+        locally_static: bool,
+        fully_static: bool,
+    );
+
+    #[wasm_bindgen(method)]
+    pub fn CreateElementNsTemplate(
+        this: &Interpreter,
+        tag: &str,
+        id: u64,
+        ns: &str,
+        locally_static: bool,
+        fully_static: bool,
+    );
+
+    #[wasm_bindgen(method)]
+    pub fn CreateTextNodeTemplate(this: &Interpreter, text: &str, root: u64, locally_static: bool);
+
+    #[wasm_bindgen(method)]
+    pub fn CreatePlaceholderTemplate(this: &Interpreter, root: u64);
 }