Converts A && A.B into A?.B (#54342)

Implements the ?. operator, replacing code like A && A.B with A?.B

BYOND Ref:
When reading A?.B, it's equivalent to A && A.B except that A is only evaluated once, even if it's a complex expression like a proc call.

code/modules/assembly/flash.dm

@@ -330,7 +330,7 @@
 	var/obj/item/organ/cyberimp/arm/flash/I = null
 
 /obj/item/assembly/flash/armimplant/burn_out()
-	if(I && I.owner)
+	if(I?.owner)
 		to_chat(I.owner, "<span class='warning'>Your photon projector implant overheats and deactivates!</span>")
 		I.Retract()
 	overheat = TRUE
@@ -338,7 +338,7 @@
 
 /obj/item/assembly/flash/armimplant/try_use_flash(mob/user = null)
 	if(overheat)
-		if(I && I.owner)
+		if(I?.owner)
 			to_chat(I.owner, "<span class='warning'>Your photon projector is running too hot to be used again so quickly!</span>")
 		return FALSE
 	overheat = TRUE

code/modules/assembly/health.dm

@@ -43,7 +43,7 @@
 		return
 
 	var/atom/A = src
-	if(connected && connected.holder)
+	if(connected?.holder)
 		A = connected.holder
 	for(A, A && !ismob(A), A=A.loc);
 	// like get_turf(), but for mobs.