Add support for individual sessions options under social auth

[NickolausDS]

Currently, using Globus Sessions changes the behavior of user ids and exposes the SOCIAL_AUTH_GLOBUS_ALLOWED_GROUPS variable. Using Sessions in DGPF shouldn't change the behavior of user ids, and admins should be able to set individual options in Globus Sessions. Ideally, this would mirror options in sessions like so:

• SOCIAL_AUTH_GLOBUS_SESSION_MESSAGE -- string
• SOCIAL_AUTH_GLOBUS_SESSION_REQUIRED_IDENTITIES -- List of user UUIDs
• SOCIAL_AUTH_GLOBUS_SESSION_REQUIRED_POLICIES -- List of policy UUIDs
• SOCIAL_AUTH_GLOBUS_SESSION_REQUIRED_MFA -- boolean
• SOCIAL_AUTH_GLOBUS_SESSION_REQUIRED_SINGLE_DOMAIN -- string

This would include the following breaking changes:

• SOCIAL_AUTH_GLOBUS_SESSIONS option would be removed
• User ids in social auth would no longer change