Better User Import Drupal

Develop/Upgrade a Drupal 8 Module for User Import. This Module can be based on any existing Module (e.g. [login to view URL]), but must fully comply with Drupal 8 Coding Standards. Probably [login to view URL] is really a good bet! But I am open to other options! Finbal Goal is the ability to provide an interface for non-admin to import users in their groups ([login to view URL]) - and to send formatted welcome mails in the process (including account information) Permission importing Users - does not require the permission to manage users! - Features: Import Users from CSV-Files - Field-Mapping can be based on machine names of profile fields. - Support importing Information into [login to view URL] (based on machine name) - Support Update of User Accounts (if already existing) -> In this case all fields are overwritten with the new information -Can import passwords from CSV file (plain text only) Role-Assignment (Special permission - users who do not have the permission can not import role assignments) - Support Assignment of Roles during import (also multiple) - It can be configured through an admin which roles can be assigned through the import (to avoid high security roles to be assigned wrongly). - Roles are added, not overwritten Unblocking and welcome mail can be sent in the process - Setting to unblock users and send welcome mail in the process - Welcome mail can be configured in the process (based on a templated configured in the module settings) Import in group (based on groups, the user can sufficient access rights to create members) - Select group in the process, where the users are supposed to be imported - Select the group role (based on existing roles, can be multiple) - if the user is already in the group, the role will be updated - if the user is already in the group and has the role, nothing happens Module should be posted to [login to view URL] (e.g. as Upgrade to [login to view URL]) - at least as patch