Support MultiEnvAuthStrategy in %ai list, chat UI settings panel

[JasonWeill]

Problem

When I was evaluating PR #478 by @markqiu, I noticed that the new QianfanEmbeddingsEndpointProvider and QianfanProvider use MultiEnvAuthStrategy, with keys QIANFAN_AK and QIANFAN_SK.

%ai list does not show either of these keys:

The Chat UI settings panel does not show inputs for either of these keys when a Qianfan model is selected:

Proposed Solution

Modify %ai list to display and check all keys when a MultiEnvAuthStrategy model is being used.

Modify the chat UI's settings panel to display inputs for all keys when a MultiEnvAuthStrategy model is being used.

Additional context

See this comment in magics.py:

jupyter-ai/packages/jupyter-ai-magics/jupyter_ai_magics/magics.py

Lines 493 to 502 in 54daef8

	# validate presence of authn credentials
	auth_strategy = self.providers[provider_id].auth_strategy
	if auth_strategy:
	# TODO: handle auth strategies besides EnvAuthStrategy
	if auth_strategy.type == "env" and auth_strategy.name not in os.environ:
	raise OSError(
	f"Authentication environment variable {auth_strategy.name} not provided.\n"
	f"An authentication token is required to use models from the {Provider.name} provider.\n"
	f"Please specify it via `%env {auth_strategy.name}=token`. "
	) from None