Stop NPCs getting confused by stashed outbounds activities

[ghost]

Summary

SUMMARY: Bugfixes "Stop NPCs getting confused by stashed outbounds activities"

Purpose of change

Fix NPCs standing around and not doing activity.

Describe the solution

#36166 was a bug where NPCs believed pulping a corpse was out of bounds of the current map, they then stashed that activity, so any people whos saves were caught up in that bug, had NPCs with that stashed activity, and in the NPC AI it checked if their mission was MISSION_ACTIVITY, which it was when you assigned them a new activity, but it found they had one already stashed, ( the pulping ) but its targets were still outbounds, therefore it set moves to 0 and did nothing , thinking that they had just been loaded into reality bubble but the corpse was not.

This shouldnt happen anymore, but for those people whos saves are affected by this still, and to hopefully avoid similar problems in future, ive cleared the stashed activity when a new activity is assigned.

they now go and do vehicle deconstruction, the save I tested on i shere. https://www.reddit.com/r/cataclysmdda/comments/ec7jww/new_players_come_here_weekly_questions_and/fbh9z2z/

Ive also neatened up the set_mission() and set_attitude() everywhere that activities are assigned, as that is encapsulated in character::assign_activity() anyway.,

Describe alternatives you've considered

N/A

Testing

save in linked reddit report - now the NPC goes and does the deconstruction when prompted.

Additional context

N/A