### Description

The [Get API key information API](https://www.elastic.co/guide/en/elasticsearch/reference/master/security-api-get-api-key.html) can currently filter the returned keys by:
 * key id/name
 * keys owned by the calling user
 * keys owned by other users, by `realm_name` and `username`

Irrespective of the filtering used, both invalidated and expired (but not yet deleted) keys will be included in the response.
In the response, keys have the `invalidated` boolean property, as well as the `expiration` property that contains the UNIX timestamp past of which the key is no longer valid for authentication.

I propose we introduce a way for the API to support retrieving:
* only valid API keys (not return invalidated keys) - using a boolean request parameter
* keys not expired before a certain timestamp - using a timestamp parameter that defaults to "now" - also note that keys' experiation date is always checked against the local node's clock
x-pack/plugin/security/src/main/java/org/elasticsearch/xpack/security/authc/ApiKeyService.java
final ApiKey.Type type;
        final long creationTime;
        final long expirationTime;
        final Boolean invalidated;
        final String hash;
        final String name;
        final int version;
        final Map<String, Object> creator;
        final String roleDescriptorsHash;
        final String limitedByRoleDescriptorsHash;
        @Nullable
        final BytesReference metadataFlattened;
        public CachedApiKeyDoc(
            ApiKey.Type type,
            long creationTime,
            long expirationTime,
            Boolean invalidated,
            String hash,
            String name,
            int version,
            Map<String, Object> creator,
            String roleDescriptorsHash,
            String limitedByRoleDescriptorsHash,
            @Nullable BytesReference metadataFlattened
        ) {