I don't quite get what problem you are facing. I assume that you need to access a class in Web assembly from Data assembly, but Data assembly already referencing Web assembly.
Can you just inject the configuration interface to your factory constructor, and use that to get the connection string?
public class EntitiesContextFactory : IDbContextFactory<EntitiesContext>
{
public EntitiesContextFactory(IConfiguration configuration){
this.configuration = configuration;
}
IConfiguration configuration;
public EntitiesContext Create()
{
return new EntitiesContext(configuration.ConnectionString);
}
}
I may misunderstand your question though.