[FIR2IR] Don't replace while loop and when branch body blocks with single expression. Skip some empty blocks.

https://youtrack.jetbrains.com/issue/KT-60264/K2-while-loop-body-block-sometimes-replaced-with-single-expression

Merge-request: KT-MR-12035
Merged-by: Vladimir Sukharev <Vladimir.Sukharev@jetbrains.com>

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

@@ -45,7 +45,10 @@ fun IReceiver.test() {
     val <iterator>: IntCell = (<this>, FiveTimes).iterator()
     while ((<this>, <iterator>).hasNext()) { // BLOCK
       val i: Int = (<this>, <iterator>).next()
-      println(message = i)
+      { // BLOCK
+        println(message = i)
+      }
     }
   }
 }
+