Add version command support to main function

[rakeshModak]

This pull request improves the command-line interface in index.js by adding support for a version flag and refining error handling.

Command-line interface improvements:

• Added support for --version and -v flags to display the current version of Calmapi, using packageInfo.version.
• Changed the handling of invalid commands to print an error message to the console instead of throwing an exception, providing a friendlier user experience.