add: google custom search + website-scraper

[iwilltry42]

This PR

1. makes the website-cleaner functions available as a package (not much code, but I think it's good to have consistency for any change done to the cleaning logic)
2. adds a super basic website-scraper tool (which is not recursive (yet)) to get website content
3. adds a basic google custom search tool leveraging the above.

Workflow:

1. LLM calls the CSE search tool and gets a list of results back
2. the LLM decides (based on title, excerpt and link), which links could be relevant
3. the LLM (optionally) calls the website-scraper tool to get more information from links it deemed relevant
4. result is returned as JSON {"answer": "<answer>", "sources": ["https://foo.com", "https://bar.de"]} which @ryanhopperlowe can use to generate citations

Issue obot-platform/obot#1935