ext4: factor out a common helper to query extent map

Factor out a new common helper ext4_map_query_blocks() from the
ext4_da_map_blocks(), it query and return the extent map status on the
inode's extent path, no logic changes.

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Link: https://patch.msgid.link/20240517124005.347221-2-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>