This adds support for the `X-Forwaded-Prefix` that rewires the paths using a custom base, with a default of `/ngclient`.
This allows using ngclient behind a proxy.
This fixes#6278
Added auth requirement on all endpoints.
Added SignIn-, Access- and Refresh-Tokens based on JWT.
Upgraded stored password to be based on PBKDF2.
Added default password assignment.
Updated logic to support auth-header and re-sign-in for tray-icon and web-ui.