🎨 Convierte el ciclo de renderizado en async

`prepare()` de `Component`, `render()` de `Region` y `Template`, y la
implementación de `ComponentRender` pasan a ser funciones async. Se
actualizan todos los componentes base, helpers, tests y ejemplos.

examples/form-controls.rs

@@ -5,6 +5,7 @@ include_locales!(LOC from "examples/locale");
 
 struct FormControls;
 
+#[async_trait]
 impl Extension for FormControls {
     fn dependencies(&self) -> Vec<ExtensionRef> {
         vec![&pagetop_aliner::Aliner, &pagetop_bootsier::Bootsier]
@@ -297,6 +298,7 @@ async fn form_controls(request: HttpRequest) -> Result<Markup, ErrorPage> {
                 ),
         )
         .render()
+        .await
 }
 
 fn form_lists() -> Form {

examples/hello-name.rs

@@ -2,6 +2,7 @@ use pagetop::prelude::*;
 
 struct HelloName;
 
+#[async_trait]
 impl Extension for HelloName {
     fn configure_router(&self, router: Router) -> Router {
         router.route("/hello/{name}", web::get(hello_name))
@@ -19,6 +20,7 @@ async fn hello_name(
             }
         }))
         .render()
+        .await
 }
 
 #[pagetop::main]

examples/hello-world.rs

@@ -2,6 +2,7 @@ use pagetop::prelude::*;
 
 struct HelloWorld;
 
+#[async_trait]
 impl Extension for HelloWorld {
     fn configure_router(&self, router: Router) -> Router {
         router.route("/", web::get(hello_world))
@@ -16,6 +17,7 @@ async fn hello_world(request: HttpRequest) -> Result<Markup, ErrorPage> {
             }
         }))
         .render()
+        .await
 }
 
 #[pagetop::main]

examples/intro-colors.rs

@@ -4,6 +4,7 @@ include_locales!(LOC from "examples/locale");
 
 struct IntroColors;
 
+#[async_trait]
 impl Extension for IntroColors {
     fn configure_router(&self, router: Router) -> Router {
         router.route("/", web::get(intro_colors))
@@ -74,6 +75,7 @@ async fn intro_colors(request: HttpRequest) -> Result<Markup, ErrorPage> {
                 ),
         )
         .render()
+        .await
 }
 
 #[pagetop::main]