support for shodan-internetdb api for passive port scanning

[brenocss]

Please describe your feature request:

Support for shodan-internetdb API to pull / validate passive ports for given hosts, for ref# projectdiscovery/uncover#21

   -passive          fetches available open ports from shodan-internetdb API
   -validate          validate open ports from shodan-internetdb API

echo hackerone.com | naabu -passive

hackerone.com:80
hackerone.com:443
hackerone.com:2082
hackerone.com:2083
hackerone.com:2086
hackerone.com:2087
hackerone.com:2096
hackerone.com:8080
hackerone.com:8443
hackerone.com:8880

echo hackerone.com | naabu -passive -scan-all-ips

hackerone.com:80
hackerone.com:443
hackerone.com:2082
hackerone.com:2083
hackerone.com:2086
hackerone.com:2087
hackerone.com:2096
hackerone.com:8080
hackerone.com:8443
hackerone.com:8880

echo hackerone.com | naabu -passive -validate

hackerone.com:80
hackerone.com:443
hackerone.com:2082
hackerone.com:2083

Describe the use case of this feature:

Adding this functionality, we could have two use cases,

• quickly look up (passively) for open ports for given list of domain / IP / subodmains
• validate passive ports from shodan-idb at run time with active scan