feat: move Expectations API out of external plugin

tests/Features/Expect/toBe.php

@@ -0,0 +1,20 @@
+<?php
+
+use PHPUnit\Framework\ExpectationFailedException;
+
+expect(true)->toBeTrue()->and(false)->toBeFalse();
+
+test('strict comparisons', function () {
+    $nuno = new stdClass();
+    $dries = new stdClass();
+
+    expect($nuno)->toBe($nuno)->not->toBe($dries);
+});
+
+test('failures', function () {
+    expect(1)->toBe(2);
+})->throws(ExpectationFailedException::class);
+
+test('not failures', function () {
+    expect(1)->not->toBe(1);
+})->throws(ExpectationFailedException::class);