stscoundrel/struct: Structs for PHP

Authored by Sampo Silvennoinen

https://github.com/stscoundrel/struct

While we wait for PHP: rfc:structs to make some traction there are other solutions that attempt to bring Structs to #PHP. This one by Sampo Silvennoinen provides an AbstractStruct class which can be extended to produce struct like behaviour. For example:

class Employee extends AbstractStruct
{    
    public string $name;    
    public string $department;
    public int $salary;
}