Convert all examples to using wasm-pack

This commit migrates all our examples to using `wasm-pack build` to
compile their code and run `wasm-bindgen`. This should make it a bit
easier to understand the examples as there's less to follow during the
build step.

Webpack projects are all using `@wasm-tool/wasm-pack-plugin` as well so
the build step is simple `npm run serve`. Other examples which retain
`build.sh` are just using `wasm-pack build` now

examples/import_js/src/lib.rs

@@ -1,6 +1,6 @@
 use wasm_bindgen::prelude::*;
 
-#[wasm_bindgen(module = "./defined-in-js")]
+#[wasm_bindgen(module = "../defined-in-js")]
 extern "C" {
     fn name() -> String;