Async Contracts

[azjezz]

i think it would be best to take advantage of Hack's async in some places here.

These contracts can be async, and probably should :

• CacheItemPoolInterface

interface CacheItemPoolInterface extends ResetInterface
{
    public function getItem(string $key): Awaitable<CacheItemInterface>;

    public function getItems(Container<string> $keys = vec[]): Awaitable<KeyedContainer<string, CacheItemInterface>>;

    public function hasItem(string $key): Awaitable<bool>;

    public function clear(): Awaitable<bool>;

    public function deleteItem(string $key):  Awaitable<bool>;

    public function deleteItems(Container<string> $keys):  Awaitable<bool>;

    public function save(CacheItemInterface $item):  Awaitable<bool>;

    public function commit(): Awaitable<bool>;
}

• CacheInterface

interface CacheInterface
{
    public function get(string $key, mixed $default = null): Awaitable<mixed>;

    public function set(string $key, mixed $value, ?DateInterval $ttl = null): Awaitable<bool>;

    public function delete(string $key): Awaitable<bool>;

    public function clear(): Awaitable<bool>;

    public function getMultiple(Container<string> $keys,mixed $default = null): Awaitable<KeyedContainer<string, mixed>>;

    public function setMultiple(KeyedContainer<string, mixed> $values,?DateInterval $ttl = null): Awaitable<bool>;

    public function deleteMultiple(Container<string> $keys): Awaitable<bool>;

    public function has(string $key): Awaitable<bool>;
}

• EventDispatcherInterface

interface EventDispatcherInterface extends ResetInterface
{
    ...
    /**
     * Dispatch an event and call the listeners.
     */
    public function dispatch(EventInterface $event): Awaitable<EventInterface>;
    ...
}

• RequestHandlerInterface

interface RequestHandlerInterface
{
    /**
     * Handle the request and return a response.
     */
    public function handle(ServerRequestInterface $request): Awaitable<ResponseInterface>;
}

• MiddlewareInterface

interface MiddlewareInterface
{
    /**
     * Process an incoming server request and return a response, optionally delegating
     * response creation to a handler.
     */
    public function process(ServerRequestInterface $request, RequestHandlerInterface $handler): Awaitable<ResponseInterface>;
}