Use manual type mapping in reflection for members from built-ins

There are cases when members deserialized from JVM classes have no JVM
signature in the proto. For example, if a member is inherited from a
built-in class (such as Map.getOrDefault in some Map implementations),
or if a member is synthesized in the compiler front-end and back-end
separately (such as enum values/valueOf). In these cases, we'll use the
naive type mapping to try to recover the signature.

 #KT-16616 Fixed
 #KT-17542 Fixed

compiler/testData/codegen/box/reflection/builtins/stringLength.kt

@@ -0,0 +1,10 @@
+// IGNORE_BACKEND: JS_IR, JS, NATIVE
+// WITH_REFLECT
+
+import kotlin.test.assertEquals
+
+fun box(): String {
+    String::class.members
+    assertEquals(2, String::length.call("OK"))
+    return "OK"
+}