feat: added list_mcp_prompts with test coverage

Why this is needed

MCP principles dictate that prompts are user-triggered. So, when an MCP server defines multiple prompts (e.g., 5 prompts), in client-side development, it’s important to allow users to discover available prompts.

Currently, without this feature, developers often:

• Hardcode prompt names in load_mcp_prompt since user might not know what all prompts are available with the server,
• Risk breaking the client if prompts are renamed or modified on the server.

This new list_mcp_prompts function:

• Lists all available prompts from the connected MCP server,
• Enables client applications to dynamically display prompt options to users,
• Prevents hardcoding, ensuring that server-side changes won’t require client updates.

Example Use Case

A client app connects to an MCP server hosting several prompts.
Instead of hardcoding prompt names, the client can:

1. Call list_mcp_prompts to retrieve all prompts.
2. Let the user choose a prompt interactively.
3. Pass the chosen prompt to load_mcp_prompt.

This matches the approach of apps like Claude Desktop, making the client more flexible and resilient to server changes.

Changes in this PR

• Added list_mcp_prompts function to retrieve available prompts.
• Added a test case to validate functionality.