Luci: Implement per-interface user login control

Examples: config login-access option username 'support' list interface 'wan' # Support user can only login from wan

config login-access option username 'user' list interface 'lan' # "user" user can only login from lan

config login-access option username 'admin' # not allowed to login from any interface.

config login-access option username 'user' list interface '*' # all interfaces are allowed to login

Users are allowed on all interfaces by default.