Enabling Custom User Input in Dashboard 2.0 Dropdown for msg Payload Transmission

### Description

I have an API that retrieves employee information based on their ID. I would like to implement a lookup feature using a Dropdown or Form component.

Since there are tens of thousands of employee records, it's not feasible to preload all options into the Dropdown. Instead, I want to allow users to input an ID directly into the Dropdown field. This ID should then be passed via msg.payload to trigger further processing — for example, using an HTTP Request node to query the employee information, and then populate the Dropdown with the matching result.

https://github.com/user-attachments/assets/7b15b19b-cd61-4269-882d-ad5589a78021

### Have you provided an initial effort estimate for this issue?

I have provided an initial effort estimate