[IMP] component: use reactivity to allow shallow renderings

With this commit, component only render child
components if they have different props (shallow
equality). Otherwise, we trust the reactivity
system to make sure that all impacted components
are updated

src/reactivity.ts

@@ -1,7 +1,7 @@
 import { Callback } from "./utils";
 
 // Allows to get the target of a Reactive (used for making a new Reactive from the underlying object)
-const TARGET = Symbol("Target");
+export const TARGET = Symbol("Target");
 // Escape hatch to prevent reactivity system to turn something into a reactive
 const SKIP = Symbol("Skip");
 // Special key to subscribe to, to be notified of key creation/deletion