temp: Add configuration option to redirect to external site when TPA account is unlinked

[xitij2000]

Testing instructions

1. Add the dummy OAuth provider
2. Try logging in using the dummy oauth provider
3. You will see an error message about an unlinked TPA account, asking you to log in.
4. Check out this branch
5. Add a site config variable called OC_REDIRECT_ON_TPA_UNLINKED_ACCOUNT with the URL to redirect to.
6. Clear cookies or us a fresh browser session, and try logging in with the dummy provider again.
7. You should be redirected to the URl set above.

Private-ref: BB-7394

[kaustavb12]

👍

Approved, subject to the resolution of the review comments

• I tested this: Tested in a sandbox.
• I read through the code
• I checked for accessibility issues
• Includes documentation
• I made sure any change in configuration variables is reflected in the corresponding client's configuration-secure repository.

[kaustavb12]

I think we should leave a comment here explaining the motivation for this change and that this is intended to be a temporary change. We should also indicate this in the PR commit message, for the benefit of the person preparing the next common branch.

[Agrendalath]

@xitij2000, please add a ticket number to the PR. Also, could you ensure we have a follow-up to create a permanent solution?

[0x29a]

Hey @xitij2000, would you like me to create a follow-up ticket to create a permanent solution for this? Redwood isn't cut yet, so it's a good chance to get rid of this code drift altogether.

[kaustavb12]

@0x29a I believe this PR via BB-7742 is the permanent solution for this problem. We won't need the changes here once that is merged and we switch to AuthN MFE. cc. @xitij2000

[0x29a]

Thanks for letting me know, @kaustavb12. I'll mention this in the code drift project.