Introduce an API endpoint to obtain public keys, that can be used to verify access tokens on other services

api/tests/functional/PublicKeysCest.php

@@ -0,0 +1,23 @@
+<?php
+declare(strict_types=1);
+
+namespace api\tests\functional;
+
+use api\tests\FunctionalTester;
+
+final class PublicKeysCest {
+
+    public function getPublicKeys(FunctionalTester $I): void {
+        $I->sendGet('/api/public-keys');
+        $I->canSeeResponseCodeIs(200);
+        $I->canSeeResponseContainsJson([
+            'keys' => [
+                [
+                    'alg' => 'ES256',
+                    'pem' => "-----BEGIN PUBLIC KEY-----\nMFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAES2Pyq9r0CyyviLaWwq0ki5uy8hr/\nZbNO++3j4XP43uLD9/GYkrKGIRl+Hu5HT+LwZvrFcEaVhPk5CvtV4zlYJg==\n-----END PUBLIC KEY-----\n",
+                ],
+            ],
+        ]);
+    }
+
+}