WP/GlobalVariablesOverride: move parse error test to its own file

Also update code comment related to the moved parse error test to include one more case where the code might bow out.

Author: rodrigoprimo

WordPress/Sniffs/WP/GlobalVariablesOverrideSniff.php

@@ -174,7 +174,7 @@ public function process_token( $stackPtr ) {
 	protected function process_list_assignment( $stackPtr ) {
 		$list_open_close = Lists::getOpenClose( $this->phpcsFile, $stackPtr );
 		if ( false === $list_open_close ) {
-			// Short array, not short list.
+			// Live coding or short array, not short list.
 			return;
 		}
 

WordPress/Tests/WP/GlobalVariablesOverrideUnitTest.1.inc

@@ -310,7 +310,3 @@ list(
 	array( $tab, $tabs ) => $not_a_wp_global,
 	get($year, $day) => &$not_a_wp_global[$year]
 ] = $array;
-
-// Live coding/parse error.
-// This has to be the last test in the file!
-list( $tab, $tabs

WordPress/Tests/WP/GlobalVariablesOverrideUnitTest.8.inc

@@ -0,0 +1,8 @@
+<?php
+
+/*
+ * Intentional parse error (missing closing parenthesis).
+ * This should be the only test in this file.
+ */
+
+list( $tab, $tabs