Support Char.code in constant evaluator, KT-46036

But do not consider Char.code a pure integer constant.

core/compiler.common/src/org/jetbrains/kotlin/builtins/StandardNames.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Copyright 2010-2021 JetBrains s.r.o. and Kotlin Programming Language contributors.
  * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
@@ -20,6 +20,8 @@ object StandardNames {
 
     @JvmField val ENUM_VALUE_OF = Name.identifier("valueOf")
 
+    @JvmField val CHAR_CODE = Name.identifier("code")
+
     @JvmField val COROUTINES_PACKAGE_FQ_NAME_RELEASE = FqName("kotlin.coroutines")
 
     @JvmField val COROUTINES_PACKAGE_FQ_NAME_EXPERIMENTAL = COROUTINES_PACKAGE_FQ_NAME_RELEASE.child(Name.identifier("experimental"))