T17000 collection revamp

[niden]

Hello!

• Type: new feature
• Link to issue: [NFR]: Collection cleanup #17000

In raising this pull request, I confirm the following:

• I have read and understood the Contributing Guidelines
• I have checked that another pull request for this purpose does not exist
• I wrote some tests for this PR
• I have updated the relevant CHANGELOG
• I have created a PR for the documentation about this change

Notable changes:

• Changed Phalcon\Support\Collection::__construct() to accept two additional opt-in parameters — bool $strictNull = false and ?string $type = null. When strictNull is true, get() returns stored null values verbatim instead of substituting the default (previous behavior was unconditional default-substitution); when type is set, every set()/init() runs through the new validateType() guard, which maps the scalar tokens int/string/bool/float/array/object to their is_* checks and treats anything else as a class/interface name compared with instanceof, throwing InvalidArgumentException on mismatch
• Changed Phalcon\Support\Collection::__serialize() to return a structured array ["data", "insensitive", "strictNull", "type"] so a serialize/unserialize round-trip restores the full configuration (previously only data survived). __unserialize() accepts both the new structured format and the legacy flat-array format, so existing serialized blobs keep deserializing without intervention
• Changed Phalcon\Support\Collection::getKeys() and Phalcon\Support\Collection::getValues() to delegate to the new keys() / values() methods and marked the get*-prefixed pair @deprecated; behavior is unchanged but new code should call keys() / values() instead
• Changed Phalcon\Contracts\Support\Collection to declare the expanded method surface (column, each, filter, first, getType, isEmpty, keys, last, map, reduce, replace, sort, values, where) so the contract matches the implementation
• Added Phalcon\Support\Collection:column(string $propertyOrMethod): array (lift a single property/method off every item, keyed by the original collection key)
• Added Phalcon\Support\Collection:each(callable $callback) (run the callback for side effects and return $this for chaining)
• Added Phalcon\Support\Collection:filter(callable $callback) (new collection of items where the callback returns truthy)
• Added Phalcon\Support\Collection:first() / last() (head/tail value or null on empty)
• Added Phalcon\Support\Collection:isEmpty(): bool, getType(): string|null (the type guard configured at construction)
• Added Phalcon\Support\Collection:keys(bool $insensitive = true) and values() (the non-get-prefixed names, with getKeys/getValues retained as deprecated wrappers)
• Added Phalcon\Support\Collection:map(callable $callback) (new collection of transformed values, keys preserved)
• Added Phalcon\Support\Collection:reduce(callable $callback, mixed $initial = null): mixed (callback signature ($accumulator, $value, $key))
• Added Phalcon\Support\Collection:replace(array $data): void (clear then init in one call)
• Added Phalcon\Support\Collection:sort(?callable $callback = null, int $order = SORT_ASC) (uasort when a callback is supplied, otherwise asort/arsort keyed by $order)
• Added Phalcon\Support\Collection:where(string $propertyOrMethod, mixed $value) (strict-equality filter via extractValue)

Thanks