Add custom labels and text to shared tab items

Story: As a shared tab user, I want to be able to add custom text and/or labels to shared tab line items so it is clear what each shared tab item is for, particularly for other shared tab users.

Use Case: Shared tab used for holiday abroad. Holiday payments are abstract company names, and when added to shared tab they are quickly forgotten what the payment is for. Hence, custom text will help clarify what each payment is for.