New schema field - group email

[cthoyt]

Related to #1385

• Add new field to resource model for capturing a group email. This might need a better name than "group email"
• Add data integrity tests. Initially, we'll only allow curating a group email if there's already an explicit primary contact person. We can consider relaxing this after a pilot and doing a review of relevant curation training materials and generating SOPs for how to communicate this policy to users/contributors
• add to resource page
• update alignment workflows to identify group emails