e2fsck: check all sparse_super backups

e2fsck: check all sparse_super backups

Teach e2fsck to look for backup super blocks in the "sparse_super"
groups, by checking group #1 first and then powers of 3^n, 5^n,
and 7^n, up to the limit of available block groups.

Export ext2fs_list_backups() function to efficiently iterate groups
for backup sb/GDT instead of checking every group.  Ensure that the
group counters do not try to overflow the 2^32-1 group limit, and
try to limit scanning to the size of the block device (if available).

Signed-off-by: Li Dongyang <dongyangli@ddn.com>
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Link: https://lore.kernel.org/r/20230904045742.827584-1-dongyangli@ddn.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>