### 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boolean property, as well as the `expiration` property that contains the UNIX timestamp past of which the key is no longer valid for authentication.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
import org.elasticsearch.core.CharArrays;
import org.elasticsearch.core.Nullable;
import org.elasticsearch.core.TimeValue;
import org.elasticsearch.core.Tuple;
import org.elasticsearch.index.query.BoolQueryBuilder;
import org.elasticsearch.index.query.QueryBuilder;
import org.elasticsearch.index.query.QueryBuilders;
import org.elasticsearch.search.SearchHit;
import org.elasticsearch.threadpool.ThreadPool;
import org.elasticsearch.xcontent.DeprecationHandler;
import org.elasticsearch.xcontent.InstantiatingObjectParser;
import org.elasticsearch.xcontent.ObjectParser;
import org.elasticsearch.xcontent.ParseField;
import org.elasticsearch.xcontent.XContentBuilder;
import org.elasticsearch.xcontent.XContentFactory;
import org.elasticsearch.xcontent.XContentLocation;
import org.elasticsearch.xcontent.XContentParser;
import org.elasticsearch.xcontent.XContentParserConfiguration;
import org.elasticsearch.xcontent.XContentType;
import org.elasticsearch.xpack.core.XPackSettings;
import org.elasticsearch.xpack.core.security.ScrollHelper;
import org.elasticsearch.xpack.core.security.action.ClearSecurityCacheAction;
import org.elasticsearch.xpack.core.security.action.ClearSecurityCacheRequest;
import org.elasticsearch.xpack.core.security.action.ClearSecurityCacheResponse;
import org.elasticsearch.xpack.core.security.action.apikey.AbstractCreateApiKeyRequest;
import org.elasticsearch.xpack.core.security.action.apikey.ApiKey;
import org.elasticsearch.xpack.core.security.action.apikey.BaseBulkUpdateApiKeyRequest;
import org.elasticsearch.xpack.core.security.action.apikey.BaseUpdateApiKeyRequest;
import org.elasticsearch.xpack.core.security.action.apikey.BulkUpdateApiKeyResponse;
import org.elasticsearch.xpack.core.security.action.apikey.CreateApiKeyResponse;