Refactor entire app using SandboxSender/Receiver in chrome-util

[io-monad]

By using SandboxSender and SandboxReceiver in @io-monad/chrome-util which is introduced in #34 , we can send messages to the sandbox without indirectly callbacks via returning event.source.postMessage.

This change would make the message flow in the extension much simpler, and reduces lots of codes. So we want to refactor the entire app by using chrome-util.