itests: expand end to end test suite to include node.js process with a wasm connection

[Roasbeef]

We should extend our test suite to also cover the browser portion. We leanred earlier this week that Go will actually change the wasm_exec.js from time to time. To increase confidence in the changes we make, we should also extend the test suite to exercise the browser portion of the system.

Steps To Completion

• [ ] Within the integration tests, spin a simple node.js process (or some headless browser system) that's loaded with the sample WASM client.
• [ ] In addition to the Go client, use the above client within the integration tests (by Go version) to exercise full end to end behavior.