Langroid

fixes:

- DocChatAgent improve check for collection missing in vecdb
- in ChainlitAgentCallback, set `llm.config.async_stream_quiet = False` to allow streaming output in chainlit

feat: LLMConfig.async_stream_quiet flag

Docs: https://langroid.github.io/langroid/notes/async-streaming/

build: minor clean/up

feat: XML-based tools

* XMLToolMessage lets you define a tool for the LLM to generate using XML rather than JSON, which helps with code-gen within tools. See [guide](https://langroid.github.io/langroid/tutorials/xml-tools/)

* File read/write and dir listing tools in [`file_tools.py`](https://github.com/langroid/langroid/blob/main/langroid/agent/tools/file_tools.py), [tests](https://github.com/langroid/langroid/blob/main/tests/main/test_file_tools.py)
* [`git_utils.py`](https://github.com/langroid/langroid/blob/main/langroid/utils/git_utils.py), [tests](https://github.com/langroid/langroid/blob/main/tests/main/test_git_utils.py)

fix: OpenAICallParams.top_p: change type to float

fix: set litellm.modify_params=True to accommodate quirks of non-OpenAI APIs without crashing.

(E.g. Anthropic APIs don't support first msg w system role)