[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/assignment.kt

@@ -0,0 +1,18 @@
+// WITH_STDLIB
+
+// FILE: test.kt
+fun box(): String {
+    val p = "O" to "K"
+
+    val ( o , k ) = p
+
+    return o + k
+}
+
+// EXPECTATIONS
+
+// test.kt:5 box:
+// test.kt:7 box: p:kotlin.Pair=kotlin.Pair
+// test.kt:9 box: p:kotlin.Pair=kotlin.Pair, o:java.lang.String="O":java.lang.String, k:java.lang.String="K":java.lang.String
+
+