Improve Talk Error Messages - email verification and banned

[lcjohnso]

Current behavior

If a user is banned or has an unverified email address (after email verification is deployed -- see https://github.com/zooniverse/talk-api/pull/311), the user is shown an error message when they try to post on Talk: not allowed to create this Comment

Expected / new behavior

Provide an informative error message that describes the reason why the user was unable to post a comment.

• For banned users: "You are banned. Email [email protected] for further information."
• For unconfirmed users: "Your account email address is not yet confirmed. Please check your email for confirmation instructions, or visit https://www.zooniverse.org/settings/email to request new confirmation email."
  • Wording based on volunteer feedback in this Freshdesk ticket.

Note Regarding Existing Behavior for DMs:

• Case 1: When trying to send a DM or access a user page (e.g., https://www.zooniverse.org/users/lcjohnso) as a banned user, the error message presented to the user is You are banned, matching the response payload from the Talk API ({"error":"You are banned"}).
• Case 2: When trying to send a DM as a user with an unconfirmed email, the error message presented to the user is You must confirm your account, matching the response payload from the Talk API ({"error":"You must confirm your account"}).
• Together: these error messages provide OK feedback, and must result from a slightly different error case than when the user is trying to add a post to a Talk thread. Further improvement is a nice-to-have -- see messages above.

Steps to replicate

Try to post using an account that is unverified or banned.