[CODESTYLE] Replace phpcs with php-cs-fixer (#1030)

* composer require --dev friendsofphp/php-cs-fixer:^2

* php-cs-fixer: ignore cache and custom local config file

* php-cs-fixer: initial config

* php-cs-fixer: replace commands in composer

* php-cs-fixer: add PSR12 "as good as it currently gets"

* php-cs-fixer: apply PSR12 to codebase

* tests: add workaround to keep unused imports for snapshot testing

* php-cs-fixer: apply no_unused_imports

* php-cs-fixer: apply array_syntax short

* php-cs-fixer: apply single_quote

* php-cs-fixer: switch ordered_imports sort_algorithm to alpha

Let's be opinionated here for consistency

* php-cs-fixer: split between non-tests and tests and share config

* php-cs-fixer: apply declare_strict_types for tests

* php-cs-fixer: apply fully_qualified_strict_types

* php-cs-fixer: apply space_after_semicolon

* php-cs-fixer: apply trailing_comma_in_multiline_array

* php-cs-fixer: apply trim_array_spaces

* php-cs-fixer: apply unary_operator_spaces

* php-cs-fixer: apply whitespace_after_comma_in_array

* php-cs-fixer: apply native_function_invocation

* php-cs-fixer: apply concat_space

* grumphp: reflect we're using phpcsfixer now

* composer remove --dev squizlabs/php_codesniffer

* gha: simplify fix-style approach

Not really necessary to remove packages and then manually prevent
unrelated commits creeping in

Co-authored-by: Barry vd. Heuvel <[email protected]>

.php_cs.tests.php

@@ -0,0 +1,22 @@
+<?php
+require __DIR__ . '/vendor/autoload.php';
+
+$finder = PhpCsFixer\Finder::create()
+    ->in(__DIR__ . '/tests')
+    ->exclude('__snapshots__');
+
+$config = require __DIR__ . '/.php_cs.common.php';
+
+// Additional rules for tests
+$config = array_merge(
+    $config,
+    [
+        'declare_strict_types' => true,
+    ]
+);
+
+return PhpCsFixer\Config::create()
+    ->setFinder($finder)
+    ->setRules($config)
+    ->setRiskyAllowed(true)
+    ->setCacheFile(__DIR__ . '/.php_cs.tests.cache');