Add `type` method to Entry::Undefined

What does this MR do and why?

Fixes the 500 error returned when a user types:

needs:
  - 

by adding the type to Entry::Undefined

Screenshots or screen recordings

Before	After

How to set up and validate locally

Try adding a needs for a job like so:

job_name:
   script: ls
   needs:
     - 

it shouldn't return a 500 anymore.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

#345156 (closed)