Addition: export "zoneExists"

[AnishBplayz]

Added a new function, api.zoneExists(id). This function checks whether a zone with the specified ID exists within the system. The ID parameter can be either a number or a string, representing the zone's index or name, respectively.

Changes Made:

• Implemented the api.zoneExists(id) function.
• Utilizes the Zones table to check for the existence of the specified zone.
• Validates the input parameter ID to ensure it is either a number or a string.
• Returns true if the zone with the specified ID exists; otherwise, it returns false.

This addition enhances the functionality of the codebase by providing a convenient method to verify the existence of zones based on their IDs.