Add additional methods for reflections that have attributes

Description

All currently attributable reflections have a single method relating to attributes.

getAttributes(?string $name = null, int $flags = 0): array

Additional methods for dealing with attributes would be a nice improvement and would simplify common approaches. I'm proposing the following methods.

getAttribute

Get a single instance of ReflectionAttribute, following the same rules as getAttributes, minus the fact that $name is required.

getAttribute(string $name, int $flags = 0): ?ReflectionAttribute

If more than one attribute matches, an exception should be thrown.

hasAttribute

Functionally identical to getAttribute, except it will return true if one or more matches are found, otherwise it returns false.

hasAttribute(string $name, int $flags = 0): bool

getNumberOfAttributes

Again, follows the same rules as getAttributes, but will return the number found. This particular method is based on the ReflectionFunctionAbstract::getNumberOfParameters method.

getNumberOfAttributes(?string $name = null, int $flags = 0): int

Inizia individuando le implementazioni esistenti di getAttributes per le reflection a cui possono essere applicati attributi e i relativi test ReflectionAttribute. Usa ReflectionFunctionAbstract::getNumberOfParameters come precedente di riferimento, quindi verifica la corrispondenza, i flags, la gestione dei duplicati e i valori restituiti dai metodi proposti per tutti i tipi di reflection a cui possono essere applicati attributi.