Check User and Group Create Date when Claiming Enterprise User

Source of this requirement: https://gitlab.com/gitlab-com/legal-and-compliance/-/issues/1298#note_1208366099

The legal definition of Enterprise User includes the following:

(2)The user account meets one of the following conditions:

• was created 2021-02-01 or later.
• has a SAML or SCIM identity tied to the organization's group.
• has a provisioned_by_group_id value that is the same as the organization's group's ID.
• is a member of the organization's group, where the subscription was purchased or renewed 2021-02-01 or later

Because we are doing an automatic claim when matching a verified domain, instead of using a SAML or SCIM identity, AND, there is no provisioned_by_group_id value (yet), we need to perform this date check.

Before we can automatically claim via verified domain, we need to check that:

1. The user was created 2021-02-01 or later.

and/or

2. The group's subscription was purchased or renewed 2021-02-01 or later

Proposal

Create a service class that will make a user "Enterprise User" if they meet the condition mentioned above. This implementation is intended to be used in multiple places in the codebase.

This class should also send e-mail notification:

Send an e-mail notification to the user (via notification address, if one is set - if not, send to primary) letting them know that they have an Enterprise Account.