Add function-calling (tools) support so the CLI provider works with AI Agents

Problem/Motivation

Config-entity AI Agents (ai_agents) drive tool use via native function calling. They call ChatInput::setChatTools() and read tool callsback from $response->getNormalized()->getTools(). CliProvider currently ignores the provided tools and never returns any tool calls, so the model has no way to invoke tools such as ai_content_review_result. In the AI Agent Explorer, this surfaces as: I'm unable to call ai_content_review_result because that tool is not available in this environment.

As a result, the CLI provider cannot be used with ai_agents or ai_content_review at all, even though the underlying CLI models are fully capable of producing structured output.

Steps to reproduce

1. Using drupal/ai:^1.4.6, ai_agents, ai_content_review, and ai_provider_cli:^1.0-dev on drupal/core-*:^11.4.
2. Create and enable an AI Agent that requires a tool (for example, the ai_content_review_result tool).
3. Select the CLI provider for the agent and run it in the AI Agent Explorer.
4. Observe that the model never calls the tool and the agent reports that the tool is unavailable.

Proposed resolution

Since CLI tools do not expose a native tool-calling API, emulate function calling at the prompt level within ai_provider_cli:

• Advertise the AiModelCapability::ChatTools capability.
• When ChatInput includes tools, serialize the OpenAI-style tool JSON schema into the prompt and instruct the model to respond with a strict envelope: "tool_calls":[{"name":"<tool_name>","arguments":{…}}]}
• Parse the envelope from CLI stdout and construct ToolsFunctionOutput objects, setting them on the normalized ChatMessage. This should mirror how native providers such as ai_provider_aws_bedrock populate tool outputs.
• Add kernel test coverage for the tool-call round trip and for the "no tools → output unchanged" case.