Code sample for JS tx-serialization

[TusharPardhe]

[TusharPardhe]

This PR is to understand the process of bounty program, as per my understanding we had to add a code sample using libraries or adding the functionality to the library itself.

If I misunderstood please use this PR as sample so everyone else can further understand the process.

Bounty DGE-94 Milestone 2

[JST5000]

Here's the updated link to the bounty referred to in this PR: https://github.com/XRPLBounties/Proposals/blob/main/bounties/0031%20JavaScript%20Code%20Samples.md

[mDuo13]

The problem here is that this code is not at all the equivalent of the Python code, which demonstrates the actual binary operations—the nuts and bolts of the serialization process. This code merely demonstrates how to use xrpl.js to serialize a transaction, which may be useful in its own way but is beside the point of the Python code sample.

Put another way, the Python code sample is for teaching how to create a client library, whereas this code sample only teaches how to use a client library that already exists.