Support for customizing screenshot folder for the web agent

[ranjanp75]

Is your feature request related to a problem? Please describe.
Screenshot folder is managed internally by the WebAgent. This makes it not safe in multi-threading, creating different objects for the webagent clashes with the same screenshot directory which causes problems.

Describe the solution you'd like
I would like to support passing the screenshot folder as an argument in the constructor

[XingWang1234]

do you know how many screenshots are used by WorldModel to plan next instruction?
seems only the latest screenshot?