Add a janitorial 'borg plunger (#85475)

## About The Pull Request
I got annoyed at not being able to plung vents when there's a clog. This
PR corrects that. I copied all of the cyborg mop attributes to make
this. This is my first PR on this server, but I did test it on a local
server, and it indeed, plungs.

## Why It's Good For The Game
More content for janitorial cyborg. They really should have a plunger,
to be honest. It just makes sense to me.

## Changelog
🆑
add: Added a cyborg plunger for janitorial modules
/🆑

code/modules/research/techweb/nodes/cyborg_nodes.dm

@@ -98,6 +98,7 @@
 		"borg_upgrade_broomer",
 		"borg_upgrade_expand",
 		"borg_upgrade_prt",
+		"borg_upgrade_plunger",
 		"borg_upgrade_selfrepair",
 		"borg_upgrade_thrusters",
 		"borg_upgrade_trashofholding",