Fix outdated escrow code samples

[mDuo13]

The _code_samples/escrow/js/ folder has several issues:

• the package.json requires both xrpl.js 3.0 and ripple-lib 0.17 (the latter is ancient and unused in the code). It's likely that ripple-lib is the source of the security issue flagged in #2783.
• the samples use the if (typeof module !== "undefined") hack, which is intended to make the same code run in both a browser via html file and in node.js, but they don't have a demo HTML file
• The samples use hard-coded secrets instead of using the faucet
• The existing tutorials like Send a Time-Held Escrow use WebSocket requests for sign-and-submit (insecure unless you know what you're doing) instead of signing using the client library