feat: add mapper for chat messages

[GabrielVasilescu04]

Description

Add the mapping methods from this wip PR: https://github.com/UiPath/uipath-langchain-python/pull/246/files

• get_chat_event receives the llm response (streamed) and returns a UiPathConversationEvent
• get_langraph_messages receives the user input from the runtime and returns a list of Langchain HumanMessages

Development Package

• Add this package as a dependency in your pyproject.toml:

[project]
dependencies = [
  # Exact version:
  "uipath-langchain==0.1.10.dev1002971200",

  # Any version from PR
  "uipath-langchain>=0.1.10.dev1002970000,<0.1.10.dev1002980000"
]

[[tool.uv.index]]
name = "testpypi"
url = "https://test.pypi.org/simple/"
publish-url = "https://test.pypi.org/legacy/"
explicit = true

[tool.uv.sources]
uipath-langchain = { index = "testpypi" }