Enhance Usability of 'send_zk_uop.ts' script

[hiroism007]

Describe the feature you would like

This script is designed to create UserOperation for ZKMynaWallet and send it to the bundler set in .env. Although several values are currently set as fixed or hardcoded, there is a need to refactor the script to make it user-friendly for everyone. It is not necessary to perform all updates at once, but here are some suggested areas for improvement:

• Create a manual for the script, detailing its purpose, functionalities, and how it operates.
• Refactor the code by modularizing functions and adding comments for better clarity and understanding.
• Modify the script to load the test RSA keys from .env, with a fallback to the test keys within the script if .env keys are unavailable.
• Update the script to load the value of userSecret from .env.

Additional context

No response