Ordering relations ui

[gabestein]

Motivation

So users can specify the order of relations they've added to specific fields

So developers can make use of relation orders in front-ends

Requirements

• Ability to sort relationships on a per-field basis via drag-and-drop handle
• If no order is specified in relationship creation, default to last

Acceptance Criteria

Mockups (if available)

https://www.figma.com/design/SqOTMElJn7fuPljfQL1gIY/PubPub-Platform?node-id=1711-73388

[3mcd]

We may want to consider re-using our strategy (or similar) in legacy for user-defined ordering of elements: https://github.com/pubpub/pubpub/blob/78b6e47e06396f9c1f545f77f1af05405a3a76fa/utils/rank.ts

But perhaps there is a more modern/postgres-native solution that would do the trick

[allisonking]

Adding link to the designs for ordering in the form fill page: https://www.figma.com/design/SqOTMElJn7fuPljfQL1gIY/PubPub-Platform?node-id=1711-73388&m=dev

might make sense to break this into two parts:

• db/api support for adding an 'order' field to relations
• ui for reordering relations (should use drag-n-drop lib we use for the form builder)