os/bluestore: Implemented create-bdev-label

os/bluestore: Implemented create-bdev-label

Introduces a helper function create_bdev_label() and a new command create-bdev-label
to write essential OSD metadata (e.g., fsid, whoami) directly into the device label
at offset 0, for use on devices where support_bdev_label == false.

Usage: ./bin/ceph-bluestore-tool --path dev/osd0 --dev dev/osd0/block create-bdev-label

If a label already exists, the function throws an error to avoid overwriting.

This lays the groundwork for eventually removing duplicated metadata from
the OSD directory for devices that don’t support native bdev labels

Signed-off-by: Jaya Prakash <jayaprakash@ibm.com>