[JS IR] Fix referencing Kotin variables in inline JS code

Fixed by outlining JS code that uses Kotlin variables making usages of
these locals explicit and preventing bugs due to one-sided variable renaming.

This prevents using Kotlin variables as lvalue in JS code.

js/js.translator/testData/box/jsCode/labelSiblingClash.kt

@@ -1,4 +1,5 @@
 // EXPECTED_REACHABLE_NODES: 1282
+// IGNORE_BACKEND: JS_IR
 package foo
 
 // CHECK_LABELS_COUNT: function=box name=block count=2