[IR] More extensive LVT tests around destructuring

All tests in this commit _pass_ to document existing behavior, but
this will change in a separate commit as we reflect desired behavior
in the test expectations.

compiler/testData/debug/localVariables/destructuring/forLoop.kt

@@ -0,0 +1,16 @@
+// WITH_STDLIB
+
+// FILE: test.kt
+fun box() {
+    val map: Map<String, String> = mapOf("1" to "23")
+    for ((a, b) in map) {
+        a + b
+    }
+}
+
+// EXPECTATIONS
+// test.kt:5 box:
+// test.kt:6 box: map:java.util.Map=java.util.Collections$SingletonMap
+// test.kt:7 box: map:java.util.Map=java.util.Collections$SingletonMap, a:java.lang.String="1":java.lang.String, b:java.lang.String="23":java.lang.String
+// test.kt:6 box: map:java.util.Map=java.util.Collections$SingletonMap
+// test.kt:9 box: map:java.util.Map=java.util.Collections$SingletonMap