Annotate a page with an inlay hint if its layout comes from a default layout

If you have code like this:

```kotlin
@file:Layout(".components.layouts.PageLayout")

package playground.pages
```

plus this:

```kotlin
package playground.pages

@Page
@Composable
fun HomePage() { ... }
```

you might not realize that the home page has a layout.

There should also be a way to go from the annotation / hint to the target layout class.