feat: add defaultPopulate property to collection config (#8934)

### 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.

docs/queries/select.mdx

@@ -97,3 +97,34 @@ const getPosts = async () => {
   <strong>Reminder:</strong>
   This is the same for [Globals](../configuration/globals) using the `/api/globals` endpoint.
 </Banner>
+```
+
+
+## `defaultPopulate` collection config property
+
+The `defaultPopulate` property allows you specify which fields to select when populating the collection from another document.
+This is especially useful for links where only the `slug` is needed instead of the entire document.
+
+```ts
+import type { CollectionConfig } from 'payload'
+
+import { lexicalEditor, LinkFeature } from '@payloadcms/richtext-lexical'
+import { slateEditor } from '@payloadcms/richtext-slate'
+
+// 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',
+  // Specify `select`.
+  defaultPopulate: {
+    slug: true,
+  },
+  fields: [
+    {
+      name: 'slug',
+      type: 'text',
+      required: true,
+    },
+  ],
+}
+```