feat: item label can save deployable robot nicknames

[chaosvolt]

Purpose of change

Just as a deployable monster's damage condition is saved in its item form and vice versa, a fun lil idea I had was for deployable bots to have their nicknames saved via the item label for their inactive form.

Describe the solution

1. In iuse_actor.cpp, changed place_monster_iuse::use so that it checks whether the item in question was labeled, and if so assigns it as the deployed monster's nickname.
2. Conversely, in monster.cpp set monster::to_item so that it checks whether the monster has a unique_name, and if so assigns it to the item being created as a label.

Describe alternatives you've considered

Adding the monster nickname to monster::init_from_item would also work, but it would enable nicknaming zombies by carving their name on the corpse. Dunno if that'd be considered desirable or not.

Testing

1. Compiled and load-tested.
2. Spawned in and undeployed a friendly hauler bot, no odd behavior observed.
3. Scrawled a name on the inactive hauler bot, it correctly deploys nicknamed now.
4. Undeploy my new friend and observe the item is still labeled.
5. For bonus lulz, deployed a mininuke hack without the skills to control it, it indeed comes out nicknamed and still eager to banish me to the shadow realm for my hubris.
6. Checked affected files for astyle.

Additional context

Checklist

[scarf005]