federated authentication + user profiles + mailing

we have to currently use several layers of determination to approve users. to change and simplify the process for 90% of users, here is a proposal:

MVP
- use in common federation (https://incommon.org/federation/) to allow anyone at a university or part of the federation to sign up for dandi
- do not activate the account, unless they also:
- create a github account and link it to their profile
- create an ORCID link
- for previous users, we can request the same for the next time they need to log in (we can force that by removing API tokens).
- create a user profile page to establish account links and connections

MVP + 1
- setup a mechanism to email registered users

MVP + 2 (bring in ReBAC/RBAC)
- this should be tied in with groups that a person can be part of
- detect if user emails bounce to determine inactive users
- add last activity to user profile page