Transforms how column prefs are stored in the database. This change
reduces the complexity of the `columns` property by removing the
unnecessary `accessor` and `active` keys.
This change is necessary in order to [maintain column state in the
URL](https://github.com/payloadcms/payload/pull/11387), where the state
itself needs to be as concise as possible. Does so in a non-breaking
way, where the old column shape is transformed as needed.
Here's an example:
Before:
```ts
[
{
accessor: "title",
active: true
}
]
```
After:
```ts
[
{
title: true
}
]
```
69c0d09437