[php-src] Issue #8728: Add `getFirstAttribute()` to `ReflectionProperty`

Issue: https://github.com/php/php-src/issues/8728 Author: SamMousa ### Description Currently the only way to retrieve property attributes is to use getAttributes(), which always returns an array. In many cases we know an attribute can not be repeated but code handling the attributes still needs to deal with it. This leads to ugly code like below, or worse assigning then checking. ```php ($reflectionProperty->getAttributes(SomeAttribute::class)[0] ?? null)?->newInstance()->doSomething(); ``` If we had a simple getFirstAttribute(string $className): null|ReflectionAttribute our code would be come more readable and communicate our intentions more clearly: ```php $reflectionProperty->getFirstAttribute(SomeAttribute::class)?->newInstance()->doSomething(); ``` While writing this I realize that this request can be broadened to include any target for attributes (ReflectionMethod, ReflectionClass etc).