Select an Identity Provider service for development

[mrjones-plip]

Describe the issue
In order to be able to actually be sure our code works for the SSO effort in #9735, we need to both have an instance that can be developed against, but also that can work in e2e tests.

Describe the improvement you'd like
Find a solution that is either cloud based or docker based (or both?!) - but that is easy to set up and test against that provides just the most limited services we need.

Describe alternatives you've considered
Pay for an existing commercial service that one of the SSO squad members recommends.