Calculate and return the number of Repositories on the dashboard
Organization list.
This PR restores some of the logic that was removed in #14032 to
calculate the number of repos on the dashboard orgs list.
Fix #16648
Replaces #16799
Signed-off-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>