Make bson-enum_error resilient to PHP 8.6 interface handler order

[GromNaN]

PHP is calling the interface_gets_implemented handlers in a different order since php/php-src#18622

Build failure detected in #1952 (comment)

The Persistable interface extends Unserializable which is the one that cannot be implemented.

[Copilot]

Pull request overview

Updates a BSON enum error PHPT to be resilient to PHP 8.6’s changed interface_gets_implemented handler order, which can alter which interface name appears in the fatal error message.

Changes:

• Switches the test expectation from --EXPECTF-- to --EXPECTREGEX--.
• Allows either MongoDB\BSON\Persistable or MongoDB\BSON\Unserializable to appear in the fatal error output.

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[alcaeus]

The Persistable interface extends Unserializable which is the one that cannot be implemented.

Small correction: Persistable also cannot be implemented directly, independent from Unserializable:

mongo-php-driver/src/BSON/Persistable.c

Lines 24 to 32 in 383bfbf

	static int php_phongo_implement_persistable(zend_class_entry* interface, zend_class_entry* class_type)
	{
	if (class_type->ce_flags & ZEND_ACC_ENUM) {
	zend_error_noreturn(E_ERROR, "Enum class %s cannot implement interface %s", ZSTR_VAL(class_type->name), ZSTR_VAL(interface->name));
	return FAILURE;
	}
	return SUCCESS;
	}

[GromNaN]

Since the check is done in both interfaces, and that's Unserializable that is mentioned in the exception message anyway, we can remove php_phongo_implement_persistable.

Or we can try to improve the exception message in php_phongo_implement_unserializable if the enum also implements Persistable. That would keep the existing exception message, which is better.