ForLoopsLowering: Handle Iterable.withIndex() where the type is a

bounded type parameter.

TODO: Handle Sequences by extending DefaultIterableHandler.

compiler/testData/codegen/box/controlStructures/forInIterableWithIndex/forInIterableTypeParameterWithIndex.kt

@@ -0,0 +1,20 @@
+// IGNORE_BACKEND_FIR: JVM_IR
+// KJS_WITH_FULL_RUNTIME
+// WITH_RUNTIME
+
+val xs = listOf("a", "b", "c", "d")
+
+fun <T : Iterable<*>> test(iterable: T): String {
+    val s = StringBuilder()
+
+    for ((index, x) in iterable.withIndex()) {
+        s.append("$index:$x;")
+    }
+
+    return s.toString()
+}
+
+fun box(): String {
+    val ss = test(xs)
+    return if (ss == "0:a;1:b;2:c;3:d;") "OK" else "fail: '$ss'"
+}