zfs.dataset.rename exists but is an private API

There is no endpoint for renaming a snapshot.

Request is that a public API endpoint be made for renaming datasets and snapshots.

Use cases from incus ZFS driver (being converted into a TN API driver):

• https://github.com/lxc/incus/blob/ebfa97fbc916aac18b5ec9aa39dfada7d19c7c82/internal/server/storage/drivers/driver_zfs.go#L726
  patchDropBlockVolumeFilesystemExtension removes the filesystem extension (e.g _ext4) from VM image block volumes

• https://github.com/lxc/incus/blob/ebfa97fbc916aac18b5ec9aa39dfada7d19c7c82/internal/server/storage/drivers/driver_zfs_volumes.go#L97C1-L99C88
  // If the cached volume size is different than the pool volume size, then we can't use the // deleted cached image volume and instead we will rename it to a random UUID so it can't // be restored in the future and a new cached image volume will be created instead.

• https://github.com/lxc/incus/blob/ebfa97fbc916aac18b5ec9aa39dfada7d19c7c82/internal/server/storage/drivers/driver_zfs_volumes.go#L97C1-L99C88
  Restoring previously deleted cached image volume

• When there are clones of a volume but someone deletes the volume
  https://github.com/lxc/incus/blob/ebfa97fbc916aac18b5ec9aa39dfada7d19c7c82/internal/server/storage/drivers/driver_zfs_volumes.go#L1520

• Renaming volume
  https://github.com/lxc/incus/blob/ebfa97fbc916aac18b5ec9aa39dfada7d19c7c82/internal/server/storage/drivers/driver_zfs_volumes.go#L1520

• Deleting snapshot but there are existing clones
  https://github.com/lxc/incus/blob/ebfa97fbc916aac18b5ec9aa39dfada7d19c7c82/internal/server/storage/drivers/driver_zfs_volumes.go#L2930