User Management

This PR will:

• Create a root user that has to be set from the env vars
• Create admin settings
• Create user roles
• Create a prehandler to verify i.e. read only setting
• Create a prehandler for disabled users

It will remove the env var named "SECRET_DISABLE_USER" as this is now available in the admin settings page

What's Changed

• feat: add user management by @bjarneo in #172

Full Changelog: v5.0.0...v5.1.0