fix deleteAction can't distinguish basePath of symbolicLink

[strugerk]

fix Appenders DeleteAction didn't work when basepath is symbolicLink. jira:https://issues.apache.org/jira/browse/LOG4J2-3342

getSortedPaths should return subFile [log4j-shix-....log],but it only return currentFile dirName [log/file] problem:Files.walkFileTree api in java.nio can't list File directly when file is symbolicLink ,it need do someThing to deal with it