Add insiders settings

[dem4ron]

• Add InsiderBenefitsForm
• Add component
• Add migration
• Progress
• Sort things out better
• Permit editing hide thingy
• Pass down props
• Disable form for non insiders
• Remove unused import
• Create an insiders settings page
• Add new components
• Add API endpoints

[iHiD]

I think these are better places into the command below (the one is already there and I'll add the insiders guard too). I prefer keeping all the logic in one place.

Also, you can't just "return" here as you need to render json, so it should be return render(json: {}) to be a valid response for a JSON API. You could also raise an error of some description like raise "Not insider" which would get caught by your block, but as we have standardised error messages in the API, that's probably not ideal.

So I would make this method:

code = User::GenerateBootcampAffiliateCouponCode.(current_user)
render json: { coupon_code: code }

or if you want to raise an error if the code is missing:

code = User::GenerateBootcampAffiliateCouponCode.(current_user)
if code 
  render json: { coupon_code: code }
else
  render_403(:could_not_generate_coupon_code)

And then you need to add translations for could_not_generate_coupon_code (see config/locales/api/en.yml)