Handle the ::class static keyword as a special case in parser/variable.js

[mreiden]

Handle T_Class as a special case when it comes after T_DOUBLE_COLON in recursive_variable_chain_scan

This solves #1135

$arrayVariable[0]::class;
$classVariable->classProp::class

[ichiriac]

The issue comes from the way PHP understands identifier https://github.com/php/php-src/blob/master/Zend/zend_language_parser.y#L325

From a certain version, identifiers are composed also by reserved and semi reserved keywords :
https://github.com/glayzzle/php-parser/blob/main/src/parser/variable.js#L161

Here an example on how it's handled from php 7.0 :

php-parser/src/parser/class.js

Line 584 in 80eb946

if (