Review and add all PHP 8.3 features

[rosswintle]

See:

• https://stitcher.io/blog/new-in-php-83
• https://php.watch/versions/8.3

• Typed Class Constants also here
• Added json_validate function also here
• Dynamic class constant and Enum member fetch support also here
• gc_status() returns additional GC information
• Random extension: New \Random\Randomizer::getBytesFromString method also here
• Random extension: New \Random\Randomizer::getFloat() and nextFloat() methods also here
• Fallback value support for PHP INI Environment Variable syntax - Not really a language feature
• PHP CLI Lint (php -l) supports linting multiple files at once Not a language feature
• class_alias() supports aliasing built-in PHP classes Not worth documenting here
• New stream_context_set_options function Too niche - not worth documenting here
• Readonly amendments
• [get_class() and get_parent_class() function calls without arguments deprecated] (https://php.watch/versions/8.3/get_class-get_parent_class-parameterless-deprecated) - A breaking change rather than a full deprecation
• #[Override] attribute
• Anonymous readonly classes
• Stack overflow detection with zend.reserved_stack_size and zend.max_allowed_stack_size - Not really a language feature
• mb_str_pad()
• Magic method closures and named arguments - Too niche
• New posix functions: posix_sysconf(), posix_pathconf(), posix_fpathconf(), and posix_eaccess() Too niche