Fixes issues with printing posters from the library management computer (#70471)

## About The Pull Request
Posters are kind of insane and they require that the poster item have
either a poster_type defined in the type or that you pass the structure
version of the poster to /new() otherwise they don't work. The weird
thing is that the structure needs to be in the contents of the item too,
or it again won't work (it won't remove the poster from your hands when
placing it). I fixed it so all you need to do is pass the structure
version of the poster to /new() on the item and it will move the
structure to the contents of the item if needed. It's still a bit insane
but it's better than it was and it fixed the bug.

Also SSLibrary.printable_posters was grabbing the directional mapping
helper of the random poster and so when you printed it and placed it,
you'd get confusing results. I made a quick fix to stop that from
happening.

## Why It's Good For The Game

Bug fixes are generally good things.
Fixes #70382
Fixes #66504


## Changelog

🆑 VexingRaven
fix: Fixed posters printed from the library console staying in your hand
when you place them
fix: Fixed Random Official Poster printed from the library console
always placing the west-facing variant no matter where you place it
/🆑

code/controllers/subsystem/library.dm

@@ -49,7 +49,8 @@ SUBSYSTEM_DEF(library)
 /datum/controller/subsystem/library/proc/prepare_official_posters()
 	printable_posters = list()
 	for(var/obj/structure/sign/poster/official/poster_type as anything in subtypesof(/obj/structure/sign/poster/official))
-		printable_posters[initial(poster_type.name)] = poster_type
+		if (initial(poster_type.printable) == TRUE) //Mostly this check exists to keep directionals from ending up in the printable list
+			printable_posters[initial(poster_type.name)] = poster_type
 
 /datum/controller/subsystem/library/proc/prepare_library_areas()
 	library_areas = typesof(/area/station/service/library) - /area/station/service/library/abandoned