Change lowering of A .= x to match fused RHS cases

Now instead of lowering to `broadcast!(identity,A,x)`, it lowers to `Broadcast.materialize!(A, Broadcast.broadcasted(identity, x))`, with all names resolved in the top module.

src/julia-syntax.scm

@@ -1721,7 +1721,7 @@
  ; expanded to something else (like a getfield)
  (if (null? lhs)
  (expand-forms e)
- (expand-forms `(call (top broadcast!) (top identity) ,lhs-view ,e))))))
+ (expand-forms `(call (|.| (top Broadcast) 'materialize!) ,lhs-view (call (|.| (top Broadcast) 'broadcasted) (top identity) ,e)))))))
 
 
 (define (expand-where body var)