Send email if a domain manager is removed from a domain

[abroddrick]

Issue description

As someone who manages a domain
I want the system to send me an email notification
so that I know when a domain manager has been removed from one of my domains

Acceptance criteria

• Email is sent to all managers of a domain when someone is removed as manager of a domain.

  • Registrar: This email should be sent if a person is removed via the registrar.
    • Note: users can remove managers via the registrar from 1) Member management and 2) the Domain pages under Domain Managers. Both should be included.
  • Django admin: NO email should be sent if a person is removed via the admin UserDomainRole table.

• this applies to org and non org members equally

Add static messaging in Django:

• Add a static message to the top of the "Are you sure?" UserDomainRole deletion page that reads: "If you remove someone from a domain here, it won't trigger any emails when you click "save.""
• Add a static message to the top of the "Are you sure?" DomainInvitation deletion page that reads: "If you cancel the domain invitation here, it won't trigger any emails. It also won't remove their domain management privileges if they already have that role assigned. Go to the User Domain Roles table if you want to remove the user from a domain."
  • Link to the "UserDomainRoles" table in that message.
• Use slim blue alert, placed right below the heading "Are you sure?" for both tables.

Additional context

No response

Links to other issues

blocked by #2370

[abroddrick]

@Katherine-Osos some questions:

1. If i delete a member from the portfolio, and that member manages domains, should this email be sent to the other domain managers?
2. I took a stab at the error messages, this is a bit different than 3019 because there is no second way to remove a user from a domain, so there is only one option that remove them and send an email. With this approach there is no way to avoid sending the email.

[Katherine-Osos]

@abroddrick

1. I would assume removing someone from a portfolio also removes them from the associated domains for that portfolio. But I don't think we've explicitly talked about that. This relates to the other thread about whether adding someone to a domain also adds them to a portfolio - that 's something we have talked about, although not in the context of sending emails.

   So anyway, yes, I would expect the domain managers to get an email when a person is removed from a portfolio and managed domains for that portfolio.

2. I adjusted the alert messages a bit, but I agree with your thinking!

[Katherine-Osos]

Added refinement label so product can weigh in on user flow for Django admin before this is implemented.