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/PluckTest.php

@@ -2,10 +2,10 @@
 
 declare(strict_types=1);
 
-namespace Tez\Utils\Tests\Arr;
+namespace Tezmanian\Utils\Tests\Arr;
 
 use PHPUnit\Framework\TestCase;
-use Tez\Utils\Arr\Pluck;
+use Tezmanian\Utils\Arr\Pluck;
 
 final class PluckTest extends TestCase
 {