isMainModule

Determines whether the provided URL represents the main entry point module.

This function checks if the provided URL corresponds to the main ESM module being executed directly. It's useful for conditionally executing code that should only run when a module is the entry point, such as starting a server or initializing an application.

It performs two key checks:

1. Verifies if the URL starts with 'file:', ensuring it is a local file.
2. Compares the URL's resolved file path with the first command-line argument (process.argv[1]), which points to the file being executed.