Add a reference table containing SSO identifications (for now, Google emails) that will be auto-granted specific roles

[mfisher87]

E.g. Hazel, Sandy, myself, Robyn, NSIDC ops folks should be auto-adminned when we register in production or in test environments.

Identifier	SSO provider	Role
Matt	Google	Admin
Hazel	Google	Admin
Robyn	Google	Admin
Etc	...	...

For now we could/should omit the SSO provider field until we alter the app to be multi-provider. We should do this anyway to hedge our bets against bugs and lack of customer support with specific providers.