Provide a way to select packages for individual users via configuration

[andersevenrud]

Currently, the only way to select what packages a user can use is:

1. Via metadata.json in a package. Which does not really solve this problem. This is usually only applicable to things that requires admin access.
2. Via blacklist in the authentication adapters. Which is kind of the opposite of what is suggested here.

So, my thought is just to add a configuration option for this, ex.:

{
  packages: {
    users: {
      username: {
        allow: ['A'],
        deny: ['B']
      }
    }
  }
}

This will allow for doing whitelisting and blacklisting.

[andersevenrud]

Related issues:

• Add blacklist implementation osjs-database-auth#2
• Add blacklist implementation osjs-pam-auth#3

[andersevenrud]

Related issues:

• User application installation and discovery support #106