crimson/os/seastore: enable SegmentCleaner to hold multiple segmented devices

crimson/os/seastore: enable SegmentCleaner to hold multiple segmented devices

For now, all segmented devices are treated the same as SEGMENTED. In the future,
there may be different kinds of segmeted devices, like SEGMENTED_NVME, SEGMENTED_SSD,
and even SEGMENTED_SATA. We plan to use a dedicated segment cleaner for each kind of
those devices, and if there are multiple devices of the same kind, they share the same
segment cleaner.

Signed-off-by: Xuehan Xu <xxhdx1985126@gmail.com>