feat(llm): add uipath openai llm

[ionmincu]

Description

Add OpenAI integration with UiPath.

Example usage

messages = [
    ChatMessage(
        role="system", content="You are a pirate with colorful personality."
    ),
    ChatMessage(role="user", content="Hello"),
]

llm = UiPathOpenAI() 
response = llm.chat(messages)

embed_model = UiPathOpenAIEmbedding()
result = embed_model.get_text_embedding("the quick brown fox jumps over the lazy dog")