[Scaffolding] checking for full model name (includes namespace) when checking for db context type

[deepchoudhery]

DbContext model's full name was not being checked. For example:

DbContext class : 

namespace blah 
{
    public class TestDbContext : DbContext 
    {}
}

Now, when we pass it to dotnet-aspnet-codegenerator, we can pass it as blah.TestDbContext or TestDbContext. Before this check, passing blah.TestDbContext would create an additional TestDbContext as it would not find the one we are looking for.