crimson/os/seastore: introduce omap_rm_keys interface in omap_manager

crimson/os/seastore: introduce omap_rm_keys interface in omap_manager

Deletion of pg_log_entry_t entries is performed by omap_rm_keys using a set.
For example, omap_rm_keys might be called with a set containing
pg_log_entry_t entries ranging from 0011.0001 to 0011.0010.
In this case, calling omap_rm_key individually for each entry is inefficient,
because each call triggers a traversal of the entire list.

To avoid this, omap_rm_keys with a set is introduced in omap_manager
to handle removal request more efficiently.

Signed-off-by: Myoungwon Oh <ohmyoungwon@gmail.com>