[Table] - There is no way to access individual "-many" relationship models in column

### Package

filament/tables

### Package Version

v4, v5

### Laravel Version

v11, v12

### Livewire Version

v3, v4

### PHP Version

PHP 8.3+

### Problem description

Currently, there is a number of columns that support displaying a list of 1-n and n-n relationship: `TextColumn::make('tags.name')`, `ImageColumn::make('colleagues.avatar')->circular()->stacked()`, however, there is no "official" way to access other fields or the model itself.

Consider:

```
// suppose we have a TagModel with columns (name, color)
TextColumn::make('tags.name')
->badge()
->color( // 'tags.color') //here, $record will be the main table $record, $state will be `tag.name`, $rowLoop will be the row loop of the row itself, not the loop of tags
```
or
```
ImageColumn::make('colleagues.avatar')
->circular()
->stacked()
->tooltip(// 'colleagues.name')
```

Currently, some cases there are workaround, for example:

```
TextColumn::make('tags.name')
->badge()
->color(function ($record, $state){
$tag = $record->tags->firstWhere('name', $state);

return Color::hex($tag->color);
})
```
but at the end of the day, it is still a workaround, it wouldnt work if there is a record with `null` name, or duplicate name (it doesnt make sense with tag name, but other models may)

Speaking of which, there is currently no workaround for the avatar example, since $user->avatar may be null, or 2 user can use the same img url.

### Expected behavior

There should be a way to access the model itself, either directly, or through a $rowLoop-type variable.

```
function($relationshipRecord) {

}
```
or
```
function($model, $relationshipRowLoop) {
$model->relationship[$relationshipRowLoop->index]
}
```

### Steps to reproduce

1. Make a new filament project
2. Make a table
3. Make a HasMany or BelongsToMany relation
4. Try to access and customize individual relation model

### Reproduction repository (issue will be closed if this is not valid)

https://github.com/filamentphp/demo

### Relevant log output

```shell

```

Start with the relationship-aware behavior of TextColumn::make('tags.name') and ImageColumn::make('colleagues.avatar'), then reproduce the examples in the linked Filament demo repository. Define how callbacks can identify each related model even when values are null or duplicated, and verify that individual relationship customization works for HasMany and BelongsToMany columns.

Written by the indexing model from the issue text.