feat: mcp prompt trigger

[hallvictoria]

Fixes Azure/azure-functions-python-worker#1846

Examples:

@app.mcp_prompt_trigger(
    arg_name="context",
    prompt_name="code_review",
    prompt_arguments=[
        func.PromptArgument("code", "The code to review", required=True),
        func.PromptArgument("language", "The programming language", required=False)
    ],
    title="Code Review",
    description="Generates a code review prompt for the given code snippet"
)
def code_review_prompt(context: func.PromptInvocationContext) -> str:
    # Access arguments from context
    code = context.arguments.get("code", "// no code provided")
    language = context.arguments.get("language", "unknown")
    
    return f"Please review the following {language} code and suggest improvements:\n\n```{language}\n{code}\n```"


# Example 2: Simple prompt with single required argument
@app.mcp_prompt_trigger(
    arg_name="context",
    prompt_name="summarize",
    prompt_arguments=[
        func.PromptArgument("text", "The text to summarize", required=True)
    ],
    title="Summarize Text",
    description="Summarizes the provided text"
)
def summarize_prompt(context: func.PromptInvocationContext) -> str:
    text = context.arguments.get("text", "No text provided")
    return f"Please provide a concise summary of the following text:\n\n{text}"


# Example 3: Prompt with no arguments
@app.mcp_prompt_trigger(
    arg_name="context",
    prompt_name="greeting",
    title="Greeting Prompt",
    description="A simple greeting prompt"
)
def greeting_prompt(context: func.PromptInvocationContext) -> str:
    return "Hello! How can I assist you today?"

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