[Enhancement] Support for Google Search API keys

[advanced4]

Feature Request
Support using an API key for Google search, which would include Google dependent sources like Linkedin, Twitter, & Trello. Google & Linkedin are particularly great sources of information, but Google is very quick to rate limit requests.

Describe the feature request or bug or other
Add a new source, "google_api" which supports using a Google Search API/CSE key

[NotoriousRebel]

Google's rate limiting is a bit much which is why we plan on adding socks5 proxy capabilities eventually. Once that is added do you think pursuing the Google API key would still be worth it?

[advanced4]

I'm not sure - it would certainly help, but I tried earlier today with regular HTTP proxies and they are all already rate-limited by Google, so thus far proxies aren't helpful.

Google API includes (I think) 100 queries per day for free, which would go a long way. A similar project https://github.com/sundowndev/PhoneInfoga/blob/v1.11/lib/googlesearch.py#L99 implemented it this way. I've only glossed over theHarvester's code base, but hopefully this is a light lift to integrate.