Enhance PM2 Process Management with Error Handling and Graceful Shutdown

[rickybharti]

Description

This update enhances PM2 process management script by:

• Adding input validation for count.
• Implementing retries for failed process starts.
• Handling graceful shutdown with SIGINT.

Key Changes

• Validates count as a positive integer.
• Starts processes with retry logic on failure.
• Tracks started and failed processes, exiting appropriately.
• Ensures PM2 disconnects gracefully on SIGINT.

Testing

• Validated various count inputs.
• Tested process start failures and retries.
• Simulated graceful shutdown with SIGINT.

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Note: SIGINT hasn't been tested extensively. Please try to test it thoroughly before approving. (@soniasingla)
Please review and provide feedback.

[soniasingla]

@rickybharti thanks for your PR, amazing work 🤗 I am working on reviewing it and will get back to you :)