CLI: better error message when mandator arg not supplied

[duaraghav8]

CLI should return a more user-friendly error response when user doesn't supply a mandatory arg to get prompt command.

eg-
(hf = Huggingface mcp server)
When we run `mcpjungle get prompt "hf__User Summary", we get:

failed to get prompt: failed to get prompt: failed to get prompt Dataset Details from MCP server hf: invalid params: MCP error -32602: Invalid arguments for prompt Dataset Details: [
  {
    "code": "invalid_type",
    "expected": "object",
    "received": "undefined",
    "path": [],
    "message": "Required"
  }
]

But if we run mcpjungle get prompt "hf__User Summary" --arg user_id=duaraghav8, then we get back a proper response.

Because we supplied the required arg user_id.

But a better error message will be something like Failed to get prompt: arg user_id is required.