Rename namespace to Tezmanian and prepare for Packagist

- Namespace Tez\Utils -> Tezmanian\Utils, package tez/* -> tezmanian/*
    - Add keywords, homepage, authors and support metadata
    - Drop VCS repositories (resolved via Packagist)
    - Remove stale composer.lock, set license holder

tests/StepTraitTest.php

@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace Tez\Utils\Tests\Enum;
+namespace Tezmanian\Utils\Tests\Enum;
 
 use PHPUnit\Framework\TestCase;
 use Tezmanian\Utils\Enum\EnumTrait;