CSV User Import

 Import a batch of users from a CSV file. The CSV file should be formatted in the following way:
 
 `externalId, lastName, firstName, email`
 
When importing a set of users using the local authentication strategy, the CSV format should be the following:

`externalId, password, lastName, firstName, email`

When an external id for the provided authentication method cannot be found, a new user will be created. When that user can be found, no new user will be created. When that user's display name is the same as their external id and a real display name is available in the CSV file, the user's display name will be updated to be the one in the CSV file. This accounts for the scenario where an external authentication provider that doesn't release the required basic profile attributes was configured and users signed into it before the full user list with appropriate basic
profile attributes was imported.