[TIMOB-7783] Android: File.createTimestamp error message on resource files is unhelpful

This issue (which has been logged twice before) created yet another panic in testing. The error message here is utterly unhelpful. If someone tries out this method on a resource file, they get a "method not supported" error. From an internal point of view, this makes complete sense--TiResourceFile is a separate class from TiFile. However, from a user point of view, they are both instances of Ti.Filesystem.File. If we're going to log a message, it should provide some information which might be useful to the end user. If we cut and pasted Don's comment from the linked bug into the log message, "Resource files don't have timestamps," it would be a vast improvement on the current situation.