Improve Whisper WASM UI example (#669)

* wip add module and js worker example

* params

* clean up, send error

* final UI with whisper webworker

* add simple instructions

candle-wasm-examples/whisper/src/lib.rs

@@ -24,6 +24,6 @@ impl Drop for Timer {
 mod app;
 mod audio;
 mod model;
-mod worker;
+pub mod worker;
 pub use app::App;
 pub use worker::Worker;