Farm Sounds DLC (basic mobs can make sounds when speaking) (#74906)

## About The Pull Request

https://user-images.githubusercontent.com/66640614/233747544-aac153b9-a100-486c-9a7a-4a436b8303b8.mov

Cows, pigs, and sheep make noise when their AI makes them speak. 
~~Also House Flipper Farm DLC came out but that's incidental.~~

## Why It's Good For The Game
It's funny, also more sound effects are fun. Gives basic mob creators
more customizability.

## Changelog
🆑 Tattle
qol: basicmobs can now make sounds when their speech is triggered
qol: pigs will now make sounds and emote on their own
sound: cows, pigs, and sheep have new sound effects!
/🆑

---------

Co-authored-by: tattle <article.disaster@gmail.com>
Co-authored-by: MrMelbert <51863163+MrMelbert@users.noreply.github.com>

code/modules/mob/living/basic/farm_animals/pig.dm

@@ -59,4 +59,5 @@
 		/datum/ai_planning_subtree/flee_target,
 		/datum/ai_planning_subtree/target_retaliate,
 		/datum/ai_planning_subtree/basic_melee_attack_subtree,
+		/datum/ai_planning_subtree/random_speech/pig,
 	)