Improve Testing for libjs

[apoorv-2204]

Is your feature request related to a problem?

we are missing some integration, unit tests, api tests more like demo tests.

Describe the solution you'd like

Add tests for

• transaction_sender.js
• api ( some api are remaining)
• Api test , some test showing different ways to use libjs

Additional context

For testing absinthe socket, we can replace windows socket. more here
https://github.com/phoenixframework/phoenix/blob/main/assets/test/socket_test.js

[apoorv-2204]

https://hexdocs.pm/phoenix/js/index.html#socket

https://github.com/phoenixframework/phoenix/blob/main/assets/test/socket_test.js