Make positions possibly negatives

[thomtrp]

Closes #5427

[greptile-apps]

PR Summary

• Updated RecordBoard.tsx to use getDraggedRecordPosition utility for calculating new positions, allowing negative values.
• Added get-dragged-record-position.util.ts utility function to handle negative positions.
• Added unit tests for getDraggedRecordPosition in get-dragged-record-position.util.test.ts.
• Modified record-position.factory.ts to support negative positions and updated related tests.
• Updated position.scalar.ts to validate and allow negative number positions.

[martmull]

LGTM

[Weiko]

LGTM @thomtrp left a small comment

[Weiko]

Since you return in your if, I think we can have something with less indentation and more readable like this. Wdyt?

export const getDraggedRecordPosition = (
  recordBeforePosition?: number,
  recordAfterPosition?: number,
): number => {
  if (isDefined(recordAfterPosition) && isDefined(recordBeforePosition)) {
    return (recordBeforePosition + recordAfterPosition) / 2;
  }

  if (isDefined(recordAfterPosition)) {
    return recordAfterPosition - 1;
  }

  if (isDefined(recordBeforePosition)) {
    return recordBeforePosition + 1;
  }

  return 1;
};