Allow relationships to be accessed by dot notation for Group blocks

[Max-Lovell]

When loading a relationship into a Select field I can do:

Select::make('variable_name')
    ->relationship(name: 'trial.trialVariables', titleAttribute: 'name'),

To chain the methods which define those relationships together. Although the relationship method isn't available for TextInputs a wrok-around is supposedly using the Group block (https://filamentphp.com/docs/3.x/forms/advanced#conditionally-saving-data-to-a-relationship):

Group::make()
    ->schema([
        TextInput::make('name')
    ])
    ->relationship(name: 'trial.trialVariables', condition: ....

Which fails with Call to undefined method App\Models\TrialFlow::trial.trialVariables(). Note both calls are in the same Builder paradigm on the same resource so the relationship is indeed there.

I've also noticed that modifyQueryUsing is not available as a parameter, which would otherwise be work-around for this issue.

I can see the Group relationship has the EntanglesStateWithSingularRelationship trait so perhaps this can be expanded? Thanks