Enhance App Handler for Multi-App Operations

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With this update, we've made significant improvements to the App Handler in heavyscript to make multi-app operations more seamless:

• Multi-App Support: Users can now specify multiple app names or use the keyword 'ALL' for start, stop, and restart operations.
• Improved App Prompts: When no app_name is provided, the script prompts users to select from available applications, making it more user-friendly.
• Enhanced Help Function: The help page has been updated to provide clear instructions on multi-app operations and using the 'ALL' keyword.
• Error Handling: The script is now more resilient with better error messaging, making it easier for users to understand any issues they might face.