Avoid class colision when using Array Resources

[Paul-Bob]

Context

As mentioned in this issue, when using Array Resources, Avo automatically generates a class based on the resource's name. For example, Avo::Resources::Movie results in the creation of a Movie class.

To prevent naming collisions with the parent app, Avo should first check if the class already exists.

We could explore the possibility of namespacing the generated class under Avo::Movie to avoid conflicts.