Serialize requirements for fetch activity

[ghost]

Summary

SUMMARY: Bugfixes "Serialize requirements for fetch activity"

Purpose of change

Fixes #34874

Describe the solution

This makes some changes to save/loading to enable NPCs to continue where they left off with their activities after loading. It saves automove route and destination_activity properly so npcs can have that restored, and sets up a proper serialization for requirement_data, so that custom requirements created on the fly during gameplay can be stored and retrieved.

Describe alternatives you've considered

N/A

Testing

Told an NPC to go and chop some trees, with a wood axe nearby, while they were walking toward the wood axe, I saved and loaded, they remembered they were walking there, and when they got there and retrieved the requirement_id stored in the backlog activity, it still pointed to a valid requirement_data object, as that had been reconstructed on load.

Also tested with construction, and they remembered their requirements there too, but this also revealed that currently, NPCs are not repeating the construction task after fetching, but thats something seperate Ill look at.

Additional context

N/A