fix: refactor Google AI Provider / helper functions and add endpoint test

[mattzh72]

Description

Refactor Google AI Provider / helper functions and add endpoint test:

• Remove service_endpoint and standardize to base_url
• Factor out common functionality in the google_ai.py folder

This PR also factors out common logic making POST requests.

Testing

1. Ran new endpoint test to make sure we can get valid first message back from Gemini:

Command:

poetry run pytest -s -vv tests/test_endpoints.py::test_gemini_pro_15_returns_valid_first_message

Results:

id='32a7eb2a-4543-4f6e-a4ff-7124e286f068' choices=[Choice(finish_reason='function_call', index=0, message=Message(content='First time user. Interesting. Initiate friendly greeting.', tool_calls=[ToolCall(id='0fa9e056-56b3-48a4-aa02-37610', type='function', function=FunctionCall(arguments='{\n  "message": "Hello, Chad. What are you thinking about right now?"\n}', name='send_message'))], role='assistant', function_call=None), logprobs=None)] created=datetime.datetime(2024, 10, 8, 23, 5, 43, 104575, tzinfo=datetime.timezone.utc) model='gemini-1.5-pro-latest' system_fingerprint=None object='chat.completion' usage=UsageStatistics(completion_tokens=41, prompt_tokens=2864, total_tokens=2905)

2. Ran model listing functionality and confirmed returned list of models:

Command

poetry run pytest -s -vv tests/test_providers.py::test_googleai   

Results:

[LLMConfig(model='gemini-1.0-pro-latest', model_endpoint_type='google_ai', model_endpoint='https://generativelanguage.googleapis.com', model_wrapper=None, context_window=30720), LLMConfig(model='gemini-1.0-pro', model_endpoint_type='google_ai', model_endpoint='https://generativelanguage.googleapis.com', model_wrapper=None, context_window=30720), LLMConfig(model='gemini-pro', model_endpoint_type='google_ai', model_endpoint='https://generativelanguage.googleapis.com', model_wrapper=None, context_window=30720), LLMConfig(model='gemini-1.0-pro-001', model_endpoint_type='google_ai', model_endpoint='https://generativelanguage.googleapis.com', model_wrapper=None, context_window=30720), LLMConfig(model='gemini-1.0-pro-vision-latest', model_endpoint_type='google_ai', model_endpoint='https://generativelan...

[vivek3141]

lgtm!