Crawl4ai tool refactoring

[rjambrecic]

Why are these changes needed?

Related issue number

Closes #1069

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.

[codecov]

Codecov Report

Attention: Patch coverage is 94.35484% with 7 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
autogen/interop/litellm/litellm_config_factory.py	92.30%	3 Missing and 3 partials ⚠️
.../interop/langchain/langchain_chat_model_factory.py	95.83%	0 Missing and 1 partial ⚠️

Files with missing lines	Coverage Δ
autogen/interop/__init__.py	100.00% <100.00%> (ø)
autogen/interop/langchain/__init__.py	100.00% <100.00%> (ø)
autogen/interop/langchain/langchain_tool.py	75.75% <ø> (ø)
autogen/interop/litellm/__init__.py	100.00% <100.00%> (ø)
autogen/oai/__init__.py	100.00% <ø> (ø)
autogen/oai/openai_utils.py	64.11% <100.00%> (+0.70%)	⬆️
...ogen/tools/experimental/browser_use/browser_use.py	88.09% <100.00%> (+3.47%)	⬆️
autogen/tools/experimental/crawl4ai/crawl4ai.py	98.03% <100.00%> (+10.71%)	⬆️
.../interop/langchain/langchain_chat_model_factory.py	95.32% <95.83%> (ø)
autogen/interop/litellm/litellm_config_factory.py	92.30% <92.30%> (ø)

... and 2 files with indirect coverage changes