Add an explicit opt-in step to join Classroom

[freecodecamp]

Add an explicit opt-in step to join Classroom

[utsab]

@raisedadead's example Auth0 app would utilize two sets of keys:

• Development ==> Will be shared with the classroom team
• Production ==> Will not be shared with the classroom team

[raisedadead]

Hey @utsab

I updated the OP to reflect the actual need for this.

I mulled over this a bit and came up with a workflow that should cover different scenarios and how all the stakeholders like freeCodeCamp API, Classroom UI, Classroom API, and our various IdP (GitHub, Google, Email via Auth0) tie together.

It's best we always define the responsibility of the stakeholders.

While it could be more convenient that a user is taken to freeCodeCamp to opt-in, I think it's better long-term that freeCodeCamp remains agnostic of apps that get built upon its core platforms.

So, I propose a more simple and modular logic in the OP.

Let me know what you think, and we can discuss the specifics in more detail over our next call.

[GuillermoFloresV]

Now being tracked inside of #479