Added modifying meta/deleting users via API

[tycrek]

Checklist

• I have read the Contributing Guidelines
• I acknowledge that any submitted code will be licensed under the ISC License
• I confirm that submitted code is my own work
• I have tested the code, and confirm that it works

Enviroment

• Operating System: Win 10
• Node version: 16
• npm version: 8

Description

This will allow developers to modify a users meta key/value pairs via the API. It also introduces the ability to delete users via the API.

To delete users, call HTTP DELETE /api/user/:id. ass will return one of 200, 404, or 500.

When setting metadata, you must use HTTP PUT /api/user/meta/:id. If the key already exists, ass will return 409 Conflict.

Additionally, I added HTTP GET /api/user/all (admin-only) to get a list of all users.

In ALL API routes, :id indicates the users unid (Unique Nano ID).

I'll document the routes more in the future. See #133 for more details.