crimson/os/seastore: change zoned device interface name from ZNS to ZBD

crimson/os/seastore: change zoned device interface name from ZNS to ZBD

We can essentially support SMR devices(HDD) and ZNS device(SSDs)
which are both subsets of Zoned Block Devices under the same interface
ZNSSegmentManager with small changes in design. Hence changing the
interface name to a more contextual name ZBDSegmentManager.
This also helps to add SMR device support for crimson.

Signed-off-by: Aravind Ramesh <aravind.ramesh@wdc.com>