feat: group by (#13138)

Supports grouping documents by specific fields within the list view.

For example, imagine having a "posts" collection with a "categories"
field. To report on each specific category, you'd traditionally filter
for each category, one at a time. This can be quite inefficient,
especially with large datasets.

Now, you can interact with all categories simultaneously, grouped by
distinct values.

Here is a simple demonstration:


https://github.com/user-attachments/assets/0dcd19d2-e983-47e6-9ea2-cfdd2424d8b5

Enable on any collection by setting the `admin.groupBy` property:

```ts
import type { CollectionConfig } from 'payload'

const MyCollection: CollectionConfig = {
  // ...
  admin: {
    groupBy: true
  }
}
```

This is currently marked as beta to gather feedback while we reach full
stability, and to leave room for API changes and other modifications.
Use at your own risk.

Note: when using `groupBy`, bulk editing is done group-by-group. In the
future we may support cross-group bulk editing.

Dependent on #13102 (merged).

---
- To see the specific tasks where the Asana app for GitHub is being
used, see below:
  - https://app.asana.com/0/0/1210774523852467

---------

Co-authored-by: Paul Popus <paul@payloadcms.com>

.github/workflows/main.yml

@@ -284,6 +284,7 @@ jobs:
           - fields__collections__Text
           - fields__collections__UI
           - fields__collections__Upload
+          - group-by
           - folders
           - hooks
           - lexical__collections__Lexical__e2e__main
@@ -419,6 +420,7 @@ jobs:
           - fields__collections__Text
           - fields__collections__UI
           - fields__collections__Upload
+          - group-by
           - folders
           - hooks
           - lexical__collections__Lexical__e2e__main