Added launch alarm for PR #4976 (#5105)

# About the pull request

Adds a looping alarm sound when the lifeboats are launched. This also
uses the function described in PR #4976 to trigger the sound. This is
NOT for adding those features, so wait until that is merged to merge
this PR.

# Explain why it's good for the game

Denies the need to make an announcement warning marines that the
lifeboats are leaving.


# Testing Photographs and Procedure
<details>
<summary>Screenshots & Videos</summary>


https://youtu.be/L8ia2OKhUUA



</details>


# Changelog
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:cl:alexguinea atticus-rezzer
add: Adds alarm sound for lifeboats when launching
/:cl:

---------

Co-authored-by: zzzmike <[email protected]>

code/modules/shuttle/computer.dm

@@ -321,7 +321,10 @@
 						to_chat(user, "[src]'s screen blinks and says \"Launch command accepted\".")
 						shipwide_ai_announcement("Launch command received. [lifeboat.id == MOBILE_SHUTTLE_LIFEBOAT_PORT ? "Port" : "Starboard"] Lifeboat doors will close in 10 seconds.")
 						addtimer(CALLBACK(lifeboat, TYPE_PROC_REF(/obj/docking_port/mobile/crashable/lifeboat, evac_launch)), 10 SECONDS)
+						lifeboat.alarm_sound_loop.start()
+						lifeboat.playing_launch_announcement_alarm = TRUE
 						return
+
 					if ("Emergency Launch")
 						launch_initiated = TRUE
 						to_chat(user, "[src]'s screen blinks and says \"Emergency Launch command accepted\".")

code/modules/shuttle/shuttles/crashable/lifeboats.dm

@@ -47,6 +47,8 @@
 	set_mode(SHUTTLE_IGNITING)
 	on_ignition()
 	setTimer(ignitionTime)
+	alarm_sound_loop.stop()
+	playing_launch_announcement_alarm = FALSE
 
 /obj/docking_port/mobile/crashable/lifeboat/crash_check()
 	. = ..()