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/webaudio/index.js

@@ -1,4 +1,4 @@
-import('./webaudio')
+import('./pkg/webaudio')
   .then(rust_module => {
     let fm = null;