Database factory, seeder and resource model_schemas should all respect scaffold --prefix

[billysmithers]

When using the --prefix from the scaffold command.

Controllers, Requests, Models and Views respect the prefix.

However Database factories and seeders do not, this would be a case of merging the namespace prefix.

This is particularly of need to factories as Laravel convention for model discovery from the factory maps the factory namespace to the model namespace.

model_schemas could merge the views prefix.

[billysmithers]

Model schemas looks to need some consideration so have left that off this PR.

This PR includes prefixes for the factory and seeder generation config - #1072