[PHP-DEV] Add spaceship assignment operator

[Nikita Popov]

Hi internals!

For consistency, we should add a spaceship assignment operator:

    $a <=>= $b;
    // same as
    $a = ($a <=> $b);

Additionally, we should add an is-identical assignment operator:

    $a ==== $b;
    // same as
    $a = ($a === $b);

Thank you for taking this proposal under consideration.

Regards,
Nikita