Add cloning AI Triggers for Easier Difficulties

[Shushishtok]

This PR is a QoL for handling AI Triggers, which can be cumbersome when handling multiple (usually 3) difficulty levels, as they require manually creating TaskForces, TeamTypes and AI Triggers for each difficulty. This aims to assist by introducing a script that can be selected to automate this process, cloning a single AI Trigger for Hard difficulty to three identical AI Triggers, each with their own duplicated TeamTypes and TaskForces.

This draws inspiration from the same script in Triggers, adjusted to work with AI Triggers instead.

• Supports both Primary and Secondary Team Types.
• Supports cases where duplicated Team Types already exist, usually due to another AI Trigger using them (in which case it will not try to duplicate them, but instead set them automatically)
• Supports cases where an AI Trigger doesn't have a Team Type assigned.

Additionally, introduces some helpers to refer to difficulty levels without having to manually write or declare them.

[Rampastring]

Looks good aside from a couple of stylistic nitpicks.