Support bulk-creation of specify user accounts via API

[bronwyncombs]

Is your feature request related to a problem? Please describe.

From Zoe:

They are looking for a way to create 100+ users using the API. ... Currently they are using a python script with direct connection to the database, not ideal. Any insights into complexity and feasibility to deliver this request appreciated.

Describe the solution you'd like
A clear and concise description of what you want to happen.

From Anusuriya:

I want to create a large number of user accounts programmatically with predefined role and, after that, email them the credentials and invite link (so that they can log in via SSO and use the credentials provided to link their account with SSO id). We will include the instruction in the email to update the password when they login first time into the system.

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

They currently use a python script as mentioned in the problem above.

Reported By
Zoe @ CSIRO NRCA via Asana

Anusuriya @ CSIRO Mineral Resources via discourse

Additional context

From Zoe:

It is not something we (NRCA) particularly need, so again low priority, but I can see how creating 100+ users would benefit from a programmatic approach.