fix ipv6 handling for remotes/sync jobs

* add square brackets to ipv6 adresses in BackupRepository if they not
already have some (we save them without in the remote config)

* in get_pull_parameters, we now create a BackupRepository first and use
  those values (which does the [] mapping), this also has the advantage
  that we have one place less were we hardcode 8007 as port

* in the ui, add square brackets for ipv6 adresses for remotes

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>

www/config/RemoteView.js

@@ -6,6 +6,9 @@ Ext.define('pmx-remotes', {
 	    calculate: function(data) {
 		let host = data.host || "localhost";
 		let port = data.port || "8007";
+		if (Proxmox.Utils.IP64_match.test(host)) {
+		    host = `[${host}]`;
+		}
 		return `${host}:${port}`;
 	    }
 	}