`toBeDeepOf()`

[faissaloux]

Hello 👋🏻

This PR introduces a new expectation: toBeDeepOf(), which makes sure that an array is deep of specific value.

Examples

$array = [1, 2, 3, 4];

expect($array)->toBeDeepOf(0); // true
expect($array)->toBeDeepOf(1); // false

$array = [1, 2, 3 => [1, 2], 4];

expect($array)->toBeDeepOf(0); // false
expect($array)->toBeDeepOf(1); // true