Convert java to kotlin and add header

Signed-off-by: Dean Birch <[email protected]>

app/src/main/java/com/nextcloud/client/preferences/SubFolderRule.kt

@@ -0,0 +1,26 @@
+/*
+ * Nextcloud Android client application
+ *
+ * @author Dean Birch
+ * Copyright (C) 2023 Dean Birch
+ * Copyright (C) 2023 Nextcloud GmbH
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.nextcloud.client.preferences
+
+enum class SubFolderRule {
+    YEAR_MONTH, YEAR, YEAR_MONTH_DAY
+}