fix(e2ee): fix certificate migration

ensure we do store in the metadata file the properly encrypted metadata

key

ensure we would update the user own certificate before eventually

encrypting again the metadata key

do this before we would try to write the metadata file and ensure it is

writtent with updated values instead of getting a copy of the old values

(before the certificate change)

Signed-off-by: Matthieu Gallien <matthieu.gallien@nextcloud.com>

[skip ci]

Author: mgallien

src/libsync/foldermetadata.cpp

@@ -602,6 +602,16 @@ QByteArray FolderMetadata::encryptedMetadata()
         return {};
     }
 
+    if (_isRootEncryptedFolder) {
+        for (auto &folderUser : _folderUsers) {
+            if (folderUser.userId == _account->davUser()) {
+                folderUser.certificatePem = _account->e2e()->getCertificate().toPem();
+            }
+        }
+
+        updateUsersEncryptedMetadataKey();
+    }
+
     QJsonObject files, folders;
     for (auto it = _files.constBegin(), end = _files.constEnd(); it != end; ++it) {
         const auto file = convertFileToJsonObject(&(*it));