Add substitution concept into JetType

In most cases it's just a map { Parameter_i => Argument_i }
Will be used when loading Raw types from Java.

Also add ClassDescriptor.getMemberScope by substitution.

core/descriptor.loader.java/src/org/jetbrains/kotlin/load/java/lazy/types/LazyJavaTypeResolver.kt

@@ -271,6 +271,8 @@ class LazyJavaTypeResolver(
             return (descriptor as ClassDescriptor).getMemberScope(getArguments())
         }
 
+        override fun computeCustomSubstitution(): TypeSubstitution? = null
+
         private val nullable = c.storageManager.createLazyValue l@ {
             when (attr.flexibility) {
                 FLEXIBLE_LOWER_BOUND -> return@l false