Migrate deprecations in core, compiler, idea, tests

Replacing deprecated Char.toInt() with Char.code and
Number.toChar() with Number.toInt().toChar(), where Number is not Int.

KT-23451

compiler/serialization/src/org/jetbrains/kotlin/serialization/AnnotationSerializer.kt

@@ -73,7 +73,7 @@ open class AnnotationSerializer(private val stringTable: DescriptorAwareStringTa
 
             override fun visitCharValue(value: CharValue, data: Unit) {
                 type = Type.CHAR
-                intValue = value.value.toLong()
+                intValue = value.value.code.toLong()
             }
 
             override fun visitDoubleValue(value: DoubleValue, data: Unit) {