This feature allows admin to set share size limit for a project.
The defaults will either come from the default values
set in the quota configuration option or via manila.conf
if the user has configured default values for quotas there.
The quota_per_share_gigabytes defaults to -1["No Limit"] always
unless changed in manila.conf by admin.
Closes-Bug: #1811943
Change-Id: Ida126c8c419b8bf4d2a194f061a0809d52b47ab8