feature: admin login

[qwertz44]

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

The "problem" is that every user in a network can access netboot.xyz webgui and make changes to the config.

Describe the solution you'd like

Add access control like a simple admin login, additionally ldap would be great.

[m-assaleh]

I have implemented this on the Webapp and it worked very well, the only thing is that I'm not sure how to manage the password resetting.

https://www.npmjs.com/package/express-basic-auth