[SSF-169] backend logic to return required actions for FM

[amywng]

ℹ️ Issue

Closes SSF-169

📝 Description

• updated getFMDonations in `manufacturers.service.ts
  • to take in current request user id and check that it matches the manufacturer representative id
  • return only matched donations
  • for each donation, return associated pending orders (where orders have at least one allocation tied to a donation item from the donation
  • for each donation, return relevant donation items (that are used in any associated order and detailsConfirmed is false)
• added DonationDetailsDto for return type
• updated controller and service tests

✔️ Verification

verified tests pass and tested call in postman

[Juwang110]

Minor things but looks great!