### What?
Adds `defaultPopulate` property to collection config that allows to
specify which fields to select when the collection is populated from
another document.
```ts
import type { CollectionConfig } from 'payload'
// The TSlug generic can be passed to have type safety for `defaultPopulate`.
// If avoided, the `defaultPopulate` type resolves to `SelectType`.
export const Pages: CollectionConfig<'pages'> = {
slug: 'pages',
// I need only slug, NOT the WHOLE CONTENT!
defaultPopulate: {
slug: true,
},
fields: [
{
name: 'slug',
type: 'text',
required: true,
},
],
}
```
### Why?
This is essential for example in case of links. You don't need the whole
document, which can contain large data but only the `slug`.
### How?
Implements `defaultPopulate` when populating relationships, including
inside of lexical / slate rich text fields.