Revert "Removes the action button from chem implants" (#36084)

* Revert "Automatic changelog compile, [ci skip]"

This reverts commit 7ea6424126.

* Revert "Automatic changelog generation for PR #36021 [ci skip]"

This reverts commit a478cf0b42.

* Revert "Update implant_chem.dm (#36021)"

This reverts commit a4df56404a.

code/game/objects/items/implants/implant_chem.dm

@@ -38,6 +38,10 @@
 		return 0
 	var/mob/living/carbon/R = imp_in
 	var/injectamount = null
+	if (cause == "action_button")
+		injectamount = reagents.total_volume
+	else
+		injectamount = cause
 	reagents.trans_to(R, injectamount)
 	to_chat(R, "<span class='italics'>You hear a faint beep.</span>")
 	if(!reagents.total_volume)