M3: restore files and folders (occ backup:browse, backup:restore)

User files are restored through the Files API so the file cache,
versions and trash stay consistent: modes new-folder (default, into
'Restored <date>/<path>'), merge (overwritten files keep their old
content as a version) and replace (extra files go to the trash). Each
file is staged under a temporary name and moved into place only after
all its blobs were verified. Any snapshot path can also be restored raw
to a local directory (disaster recovery).

Tested on NC34: all three modes restore checksum-identical files, the
overwritten content is kept as a version, the extra file is in the
trash, no temporary files remain.

appinfo/info.xml

@@ -5,7 +5,7 @@
     <name>NG Backup</name>
     <summary>Encrypted, incremental backups of your Nextcloud with restore from the web interface</summary>
     <description><![CDATA[Work in progress, not ready for use.]]></description>
-    <version>0.0.3</version>
+    <version>0.0.4</version>
     <licence>agpl</licence>
     <author>Dillard Blom</author>
     <namespace>NgBackup</namespace>
@@ -30,5 +30,7 @@
         <command>OCA\NgBackup\Command\RunBackup</command>
         <command>OCA\NgBackup\Command\Status</command>
         <command>OCA\NgBackup\Command\ListSnapshots</command>
+        <command>OCA\NgBackup\Command\Browse</command>
+        <command>OCA\NgBackup\Command\Restore</command>
     </commands>
 </info>