[FIR] Extract LHS receiver of assignment operator statements

#KT-53490 Fixed

compiler/testData/ir/irText/expressions/javaSyntheticGenericPropretyAccess.fir.kt.txt

@@ -7,5 +7,8 @@ fun <F : Any?> test(j: J<F>) {
     <receiver>.setFoo(x = <unary>.inc())
     <unary>
   } /*~> Unit */
-  j.setFoo(x = j.getFoo().plus(other = 1))
+  { // BLOCK
+    val <receiver>: J<F> = j
+    <receiver>.setFoo(x = <receiver>.getFoo().plus(other = 1))
+  }
 }