Function addChildSignal

addChildSignal<T>(
    items: WritableSignal<T[] | null>,
    unshift: boolean,
    ...children: T[],
): void
Update the given items signal reference by adding new children.
- Uses array spread syntax to update.
- Adds at the beginning or end based on the unshift parameter.
Type Parameters
- T
Parameters
- items: WritableSignal<T[] | null>
  signal reference
- unshift: boolean
  whether to insert before other items
- ...children: T[]
  to add
Returns void