Move 3rd-party libs to a dedicated directory

[MAILPOET-2545]

RoboFile.php

@@ -373,10 +373,6 @@ class RoboFile extends \Robo\Tasks {
       ->rawArg('--runtime-set testVersion 5.6-7.3')
       ->arg('--ignore=' . implode(',', [
           'lib/Config/PopulatorData/Templates',
-          'lib/Util/CSS.php',
-          'lib/Util/Sudzy',
-          'lib/Util/pQuery',
-          'lib/Util/XLSXWriter.php',
           'tests/_data',
           'tests/_output',
           'tests/_support/_generated',

build.sh

@@ -70,6 +70,7 @@ cp -Rf lang $plugin_name
 cp -RfL assets $plugin_name
 cp -Rf generated $plugin_name
 cp -Rf lib $plugin_name
+cp -Rf lib-3rd-party $plugin_name
 cp -Rf vendor $plugin_name
 cp -Rf vendor-prefixed $plugin_name
 cp -Rf views $plugin_name

composer.json

@@ -38,15 +38,15 @@
   },
   "autoload": {
     "classmap": [
+      "lib-3rd-party",
       "vendor-prefixed"
     ],
     "files": [
-      "lib/Util/ArrayColumn.php"
+      "lib-3rd-party/ArrayColumn.php"
     ],
     "psr-4": {
       "MailPoet\\": "lib/",
       "MailPoetVendor\\": "vendor-prefixed/",
-      "Sudzy\\": "lib/Util/Sudzy",
       "MailPoetGenerated\\": "generated/"
     }
   },

lib/Util/pQuery/pQuery.php

@@ -3,6 +3,7 @@
 namespace MailPoet\Util\pQuery;
 
 // extend pQuery class to use UTF-8 encoding when getting elements' inner/outer text
+// phpcs:ignore Squiz.Classes.ValidClassName
 class pQuery extends \pQuery {
   public static function parseStr($html) {
     $parser = new Html5Parser($html);