[CRITEO] Add a property to force canonicalization of hostname with WebHdfsFileSystem

[Willymontaz]

WebHdfsFileSystem does not enforce SPNEGO when using connectionFactory because the jdk automatically performs SPNEGO when a response is received with 401 + header 'WWW-Authenticate: Negotiate'.

This part actually works fine, WebHdfsFileSystem gets a delegation token with SPNEGO and continues with this token.

However, if we expect hostname canonicalization, the jdk has some restrictions and forces the canonical hostname to be a longer format of the hostname, otherwise it is ignored. This behavior can be found in class sun.security.krb5.PrincipalName, in the constructor:

                    // RFC4120 does not recommend canonicalizing a hostname.
                    // However, for compatibility reason, we will try
                    // canonicalize it and see if the output looks better.

                    String canonicalized = (InetAddress.getByName(hostName)).
                            getCanonicalHostName();

                    // Looks if canonicalized is a longer format of hostName,
                    // we accept cases like
                    //     bunny -> bunny.rabbit.hole
                    if (canonicalized.toLowerCase(Locale.ENGLISH).startsWith(
                                hostName.toLowerCase(Locale.ENGLISH)+".")) {
                        hostName = canonicalized;
                    }

This means that when reaching namenodes via consul for instance (ex. hadoop-hdfs-namenode-active-root.query.consul.preprod.crto.in) the canonicalization is purely ignored by the jdk because the canonicalized hostname is something like {something}.{dc}.hpc.criteo.(pre)prod

This commit allows the possibility to canonicalize namenode addresses in WebHdfsFileSystem to overcome this issue. This behavior is activated by the property dfs.webhdfs.host.canonicalize.enabled (default: false)