Implement websurfer agent

[rjambrecic]

Why are these changes needed?

We want to be able to use:

config_list = [{"model": "gpt-4o-mini", "api_key": os.environ["OPENAI_API_KEY"]}]

llm_config = {
    "config_list": config_list,
}

web_tool="browser_use" # or "crawl4ai"
user_proxy = UserProxyAgent(name="user_proxy", human_input_mode="NEVER")
websurfer = WebSurferAgent(name="WebSurfer", llm_config=llm_config, web_tool=web_tool)

websurfer_tools = websurfer.tools
# WebSurferAgent has a list of tools which are registered for LLM
# We need to register the tools for execution with the UserProxyAgent
for tool in websurfer_tools:
    tool.register_for_execution(user_proxy)

user_proxy.initiate_chat(
    recipient=websurfer,
    message="Get info from https://docs.ag2.ai/docs/Home",
    max_turns=2,
)

Related issue number

Closes #660

Checks

• I've included any doc changes needed for https://docs.ag2.ai/. See https://docs.ag2.ai/docs/contributor-guide/documentation to build and test documentation locally.
• I've added tests (if relevant) corresponding to the changes introduced in this PR.
• I've made sure all auto checks have passed.