Added support for container commands (#1049)

* Added support for container commands FUNCTION LOAD, FUNCTION DELETE and FCALL

* Changed ContainerInterface and AbstractContainer

* Re-implement logic of abstract methods

---------

Co-authored-by: Vladyslav Vildanov <vladyslavvildanov@Vladyslav-Vildanov-MacBook-Pro.local>

tests/Predis/Command/Strategy/SubcommandStrategyResolverTest.php

@@ -0,0 +1,51 @@
+<?php
+
+/*
+ * This file is part of the Predis package.
+ *
+ * (c) 2009-2020 Daniele Alessandri
+ * (c) 2021-2023 Till Krüss
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Predis\Command\Strategy;
+
+use InvalidArgumentException;
+use PHPUnit\Framework\TestCase;
+use Predis\Command\Strategy\ContainerCommands\Functions\LoadStrategy;
+
+class SubcommandStrategyResolverTest extends TestCase
+{
+    /**
+     * @var StrategyResolverInterface
+     */
+    private $resolver;
+
+    protected function setUp(): void
+    {
+        $this->resolver = new SubcommandStrategyResolver();
+    }
+
+    /**
+     * @return void
+     */
+    public function testResolveCorrectStrategy(): void
+    {
+        $expectedStrategy = new LoadStrategy();
+
+        $this->assertEquals($expectedStrategy, $this->resolver->resolve('functions', 'load'));
+    }
+
+    /**
+     * @return void
+     */
+    public function testResolveThrowsExceptionOnNonExistingStrategy(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('Non-existing container command given');
+
+        $this->resolver->resolve('foo', 'bar');
+    }
+}