KT-36047 Support when-with-subject in optimized 'when' generators

compiler/testData/codegen/bytecodeText/when/tableSwitchWithSubjectVal.kt

@@ -0,0 +1,11 @@
+fun foo(x: Int): String {
+    return when (val y = x) {
+        101 -> "1"
+        102 -> "2"
+        103 -> "3"
+        else -> "else"
+    }
+}
+
+// 0 LOOKUPSWITCH
+// 1 TABLESWITCH