WebSurfer Documentation and Fixes

[husseinmozannar]

This should not change how the WebSurfer operates in any way except for summarization/QA tool.

• adds documentation to web surfer
• adds documentation to playwright controller and exposes it
• cleans up code of web surfer
• adds markdown converter for summarization tool
• add on_message_stream with exposing inner messages
• adds model usage stats to web surfer
• add unit tests

Related issue number

Closes :
#4573
#4567
#4565
#4467

[husseinmozannar]

Ready for review. Hopefully can be merged this week

@afourney this shouldn't change how the websurfer works, but added tests/docs/cleanup/markitdown for summarization. Take your time in review, this will probably be how the code looks like for a while.

@ekzhu I added tests for playwright controller and websurfer. I had to check private attributes for the test and so plastered "# pyright: ignore[reportPrivateUsage]" everywhere, don't know how to otherwise. I do not want to expose these attributes otherwise

[husseinmozannar]

when reviewing, please take a look at how I changed the toml file to do playwright install, thanks!

[husseinmozannar]

the test pass locally.. and passed before the latest commit while I didn't change any of the code functionally..

[afourney]

Looks good, as per the discussion.