Add email validation for account users email domain

• Type: Story
• Status: Closed
• Priority: Minor
• Resolution: Completed
• Affects Version/s: None
• Fix Version/s: Master
• Component/s: User Management > Business Accounts
• Labels:
  • 7.3-ce-ga5
  • UandSM-jun20
  • fc_20_06
  • planned_for_7.3
• Epic Link: Account Email Domain
• Sprint: U&SM| S03 Sprint 24 |5.26-6.9, U&SM| S03 Sprint 25 | 6.9-23, U&SM| S03 Sprint 26 | 6.23-7.7, U&SM| S03 Sprint 27 | 7.7-7.21
• Git Pull Request: https://github.com/drewbrokke/liferay-portal/pull/1097

Description
If LPS-112519 is enabled, then Account Managers can input a list of email domains for an account. Each account user added to the account must have an email address matching one of the listed domains. This provides an additional layer of security to prevent unauthorized account users from being added to an account. 

For example, if the email domains acme.com and acme.xyz are listed as valid domains, 2B account administrators can only add users with matching domains like [e-mail]. Users like [e-mail] cannot be added to the account.

However, B2 account managers can still explicitly add account users with non-matching email domains. If [e-mail] is a contractor for example, the 2B account administrator can make a request to the B2 account manager.

Acceptance Criteria

1. If LPS-112519 is enabled, account managers can input a list of email domains in an account's details page
2. When B2 account managers try to add an account user with a non-matching domain, the account manager must accept a warning confirmation
3. 2B account administrators cannot add account users with non-matching domains

Design
https://www.figma.com/file/ETsCBBQqB2qIJZlWXz42nr/lps-97617-add-new-users