[Backend] Implement role request feature

[amlannandy]

Is your feature request related to a problem? Please describe. The Web app currently has a button to request a change in role, but the functionality is not present in the server.

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

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

Additional context I'll soon submit a PR for this.