[Login] Add support for signing in to Black-flagged Sites

[pmusolino]

Description

When users attempt to log into the app with a black-flagged site URL, they receive an error message stating the URL is invalid and are unable to proceed with login.

This task should update the login flow to gracefully handle this case by directing those users to use site credentials instead of WordPress.com.

Tasks

Beta Give feedback

1. Improve error parsing for the WPCom endpoint /connect/site-info to allow identifying black-flagged websites. #12775
   feature: login type: task +2
2. Direct black-flagged websites to use site credentials instead of failing. #12779
   feature: login type: enhancement +2
3. Hide Jeptack upselling points from the app when using a black-flagged website. #12782
   feature: login priority: medium type: enhancement +3
   
4. Check if site is black-flagged on app launch #12789
   feature: login type: enhancement +2
   
5. [Black-flagged websites] Tracking #12790
   category: tracks feature: login +2
   

References

peaMlT-JX-p2
woocommerce/woocommerce-ios#13348

[dangermattic]

Thanks for reporting! 👍