Add first and last name to add new user form on multisite

[andyburnsco]

When creating users on multisite, you only get to add their username and email (user-new.php template > add new user). On single site installs, users can add first name, last name and website. (user-new.php)

On multisite at /wp-admin/user-new.php, it should allow for the first and last name fields to the Add New User form.

Is there a reason for this difference? For WP sites that have CRM integration, not getting core fields of a contact makes adding a user more difficult. Namely, duplicates are created. It is most important to have these fields available on each site not just the network level user creation form at /wp-admin/network/user-new.php.

Ref: ​https://premium.wpmudev.org/forums/topic/multisite-first-and-last-name-when-add-new-user/

[andyburnsco]

Duplicate of #18163.