Support indy concatenation

compiler/testData/codegen/bytecodeText/stringOperations/concatDynamicIndy.kt

@@ -0,0 +1,23 @@
+// KOTLIN_CONFIGURATION_FLAGS: RUNTIME_STRING_CONCAT=indy
+// JVM_TARGET: 9
+class A
+
+inline fun test(s: (String) -> Unit) {
+    s("456")
+}
+
+fun box(a: String, b: String?) {
+    val s = a + "1" + "2" + 3 + 4L + b + 5.0 + 6F + '7' + A() + true + false + 1u
+
+    a.plus(b)
+    b?.plus(a)
+    val ref1 = a::plus
+    val ref2 = b::plus
+
+    test("123"::plus)
+}
+
+// 0 INVOKEDYNAMIC makeConcatWithConstants
+// 6 INVOKEDYNAMIC makeConcat
+// 0 append
+// 0 stringPlus