migrate to "export default"

also, set no-use-before-define in linter

src/backupformat/rsync.js

@@ -1,14 +1,13 @@
 import assert from 'node:assert';
 import async from 'async';
-import * as backupSites from '../backupsites.js';
+import backupSites from '../backupsites.js';
 import BoxError from '../boxerror.js';
 import DataLayout from '../datalayout.js';
-import { DecryptStream } from '../hush.js';
 import debugModule from 'debug';
-import { EncryptStream } from '../hush.js';
+import hush from '../hush.js';
+const { DecryptStream, EncryptStream } = hush;
 import fs from 'node:fs';
 import HashStream from '../hash-stream.js';
-import * as hush from '../hush.js';
 import path from 'node:path';
 import paths from '../paths.js';
 import ProgressStream from '../progress-stream.js';
@@ -16,7 +15,7 @@ import promiseRetry from '../promise-retry.js';
 import safe from 'safetydance';
 import shellModule from '../shell.js';
 import stream from 'stream/promises';
-import * as syncer from '../syncer.js';
+import syncer from '../syncer.js';
 import util from 'node:util';
 
 const debug = debugModule('box:backupformat/rsync');
@@ -25,15 +24,6 @@ const shell = shellModule('backupformat/rsync');
 const _saveFsMetadata = saveFsMetadata;
 const _restoreFsMetadata = restoreFsMetadata;
 
-export {
-    download,
-    upload,
-    verify,
-    getFileExtension,
-    copy,
-    _saveFsMetadata,
-    _restoreFsMetadata,
-};
 
 async function addFile(sourceFile, encryption, uploader, progressCallback) {
     assert.strictEqual(typeof sourceFile, 'string');
@@ -382,3 +372,12 @@ async function verify(backupSite, remotePath, integrityMap, progressCallback) {
     };
 }
 
+export default {
+    download,
+    upload,
+    verify,
+    getFileExtension,
+    copy,
+    _saveFsMetadata,
+    _restoreFsMetadata,
+};

src/backupformat/tgz.js

@@ -1,9 +1,10 @@
 import assert from 'node:assert';
-import * as backupSites from '../backupsites.js';
+import backupSites from '../backupsites.js';
 import BoxError from '../boxerror.js';
 import DataLayout from '../datalayout.js';
 import debugModule from 'debug';
-import { DecryptStream, EncryptStream } from '../hush.js';
+import hush from '../hush.js';
+const { DecryptStream, EncryptStream } = hush;
 import fs from 'node:fs';
 import HashStream from '../hash-stream.js';
 import path from 'node:path';
@@ -347,7 +348,7 @@ function getFileExtension(encryption) {
 
 const _EnsureFileSizeStream = EnsureFileSizeStream;
 
-export {
+export default {
     download,
     upload,
     verify,