e2fsprogs: add quota library to e2fsprogs

e2fsprogs: add quota library to e2fsprogs

This patch adds the quota library (ported form Jan Kara's quota-tools) in
e2fsprogs in order to make quotas as a first class supported feature in Ext4.
This patch also provides interface in lib/quota/mkquota.h that will be used by
mke2fs, tune2fs, e2fsck, etc. to initialize and update quota files.
This first version of the quota library does not support reading existing quota
files. This support will be added in the near future.
Thanks to Jan Kara for his work on quota-tools. Most of the files in this patch
are taken as-is from quota tools and were simply modified to work with
libext2fs in e2fsprogs.

Signed-off-by: Aditya Kali <adityakali@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>