Rfc: inner classes

[withinboredom]

This is the implementation for inner classes as defined in https://wiki.php.net/rfc/short-and-inner-classes

There is quite a lot going on here, so here's an overview of the changes (thanks AI):

Changes

File(s)	Change Summary
Zend/{zend.h, zend_ast.h, zend_compile.c, zend_compile.h, zend_execute.c, zend_language_parser.y, zend_language_scanner.l, zend_object_handlers.c, zend_opcode.c, zend_vm_def.h, zend_vm_execute.h, zend_vm_handlers.h, zend_vm_opcodes.c, zend_vm_opcodes.h}	Added support for inner (nested) classes including a new AST node (ZEND_AST_INNER_CLASS), additional structure members (required_scope, lexical_scope, required_scope_absolute), updated compile functions (zend_compile_inner_class_ref, zend_resolve_nested_class_name), new token (T_INNER_REF) handling, opcode definitions, and enhanced visibility checks.
ext/reflection/{php_reflection.c, php_reflection.stub.php, php_reflection_arginfo.h}	Extended the ReflectionClass API with new methods: isInnerClass, isPrivate, isProtected, and isPublic to determine inner class status and visibility.
ext/opcache/zend_persist.c	Introduced zend_update_required_scope to update the required_scope and lexical_scope properties during class table persistence, ensuring proper reference management.
ext/tokenizer/{tokenizer_data.c, tokenizer_data.stub.php, tokenizer_data_arginfo.h}	Added support for a new token (T_INNER_REF) for inner class references by updating token recognition rules and constant definitions.
Zend/tests/errmsg/errmsg_027.phpt, ext/reflection/tests/bug74454.phpt	Updated expected error messages to clarify the syntax and parsing errors related to nested class declarations.
tests/classes/inner_classes/*.phpt	Added numerous test cases covering inner class declarations, access modifiers (including public, private, protected, and specialized modifiers), autoloading, inheritance, readonly properties, return types, static variables, and visibility rules.