feat: convert file manager into a plugin

drizzle/sqlite/0033_careful_random.sql

@@ -0,0 +1,5 @@
+-- file_manager_pinned, file_manager_recent, file_manager_shortcuts and
+-- transfer_recent are adopted (renamed, not dropped) by the file-manager
+-- plugin's own migration, which runs at plugin activation, after core's
+-- drizzle migrations. A DROP TABLE here would run first and delete the data.
+SELECT 1;