add mixing of required mods and freemod to !mp mods

[ILW8]

Example: !mp mods FM+NF forces NF and allows freemod (while removing SD from freemod as it isn't compatible with NF).

[Copilot]

Pull Request Overview

This PR enhances the !mp mods command to support mixing required mods with freemod functionality. Previously, the command only supported either freemod (FM) or regular mods, but now allows combinations like FM+NF to force specific mods while enabling freemod for others.

• Refactored mod parsing logic to process each mod individually instead of treating freemod as a special case
• Added compatibility checking to remove incompatible mods from the allowed freemod list when required mods are present
• Improved mod conflict resolution by removing duplicate required mods from allowed mods list

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