metadata: move models to Arsenal

The models are the module BucketInfo, ObjectMD, WebsiteConfiguration and
ReplicationConfiguration.
These models are needed for the S3SOFS feature into the cdmiclient
repository. The S3 one does not export modules and shared ones are in
Arsenal so move these model modules to it.

lib/api/apiUtils/bucket/bucketCreation.js

@@ -3,7 +3,7 @@ const async = require('async');
 const { errors } = require('arsenal');
 
 const acl = require('../../../metadata/acl');
-const BucketInfo = require('../../../metadata/BucketInfo');
+const BucketInfo = require('arsenal').models.BucketInfo;
 const constants = require('../../../../constants');
 const createKeyForUserBucket = require('./createKeyForUserBucket');
 const metadata = require('../../../metadata/wrapper');

lib/api/apiUtils/bucket/bucketWebsite.js

@@ -2,8 +2,9 @@ const { parseString } = require('xml2js');
 const { errors, s3middleware } = require('arsenal');
 
 const escapeForXml = s3middleware.escapeForXml;
-const { WebsiteConfiguration }
-    = require('../../../metadata/WebsiteConfiguration');
+const { WebsiteConfiguration } =
+  require('arsenal').models.WebsiteConfiguration;
+
 /*
    Format of xml request:
 

lib/api/apiUtils/bucket/getReplicationConfiguration.js

@@ -1,5 +1,6 @@
 const parseXML = require('../../../utilities/parseXML');
-const ReplicationConfiguration = require('./models/ReplicationConfiguration');
+const ReplicationConfiguration =
+  require('arsenal').models.ReplicationConfiguration;
 
 // Handle the steps for returning a valid replication configuration object.
 function getReplicationConfiguration(xml, log, cb) {