php: Support new features

[nsfisis]

Name of the lexer
php

Support new features added in PHP 8.x.

TODO

• enum
  • php: Support enum definition #2171
• octal number prefix
  • php: Support alternative notation of octal number literal (0o prefix) #2170
• asymmetric visibility
  • php: Support asymmetric visibility #2173
• property hook
• typed class constants
  • php: Support typed class constants #2174
• added/removed built-in functions
  • php: Update built-in functions (rake builtins:php) #2175

I'll submit pull request for each features.