Features:
+* maybe introduce an OSC sequence that signals when we ask for a password, so
+ that terminal emulators can maybe connect a password manager or so, and
+ highlight things specially.
+
+* Port pidref_namespace_open() to use PIDFD_GET_MNT_NAMESPACE and related
+ ioctls to get nsfds directly from pidfds.
+
+* start using STATX_SUBVOL in btrfs_is_subvol(). Also, make use of it
+ generically, so that image discovery recognizes bcachefs subvols too.
+
* format-table: introduce new cell type for strings with ansi sequences in
them. display them in regular output mode (via strip_tab_ansi()), but
suppress them in json mode.