### 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boolean property, as well as the `expiration` property that contains the UNIX timestamp past of which the key is no longer valid for authentication.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/test/java/org/elasticsearch/xpack/security/authc/ApiKeyServiceTests.java
import org.elasticsearch.xpack.core.security.action.apikey.CreateApiKeyResponse;
import org.elasticsearch.xpack.core.security.action.apikey.CrossClusterApiKeyRoleDescriptorBuilder;
import org.elasticsearch.xpack.core.security.action.apikey.GetApiKeyResponse;
import org.elasticsearch.xpack.core.security.action.apikey.InvalidateApiKeyResponse;
import org.elasticsearch.xpack.core.security.authc.Authentication;
import org.elasticsearch.xpack.core.security.authc.Authentication.RealmRef;
import org.elasticsearch.xpack.core.security.authc.AuthenticationField;
import org.elasticsearch.xpack.core.security.authc.AuthenticationResult;
import org.elasticsearch.xpack.core.security.authc.AuthenticationTestHelper;
import org.elasticsearch.xpack.core.security.authc.AuthenticationTests;
import org.elasticsearch.xpack.core.security.authc.RealmDomain;
import org.elasticsearch.xpack.core.security.authc.support.AuthenticationContextSerializer;
import org.elasticsearch.xpack.core.security.authc.support.Hasher;
import org.elasticsearch.xpack.core.security.authz.RoleDescriptor;
import org.elasticsearch.xpack.core.security.authz.RoleDescriptorTests;
import org.elasticsearch.xpack.core.security.authz.RoleRestrictionTests;
import org.elasticsearch.xpack.core.security.authz.privilege.ApplicationPrivilege;
import org.elasticsearch.xpack.core.security.authz.privilege.ClusterPrivilegeResolver;
import org.elasticsearch.xpack.core.security.authz.store.RoleReference;
import org.elasticsearch.xpack.core.security.user.User;
import org.elasticsearch.xpack.security.authc.ApiKeyService.ApiKeyCredentials;
import org.elasticsearch.xpack.security.authc.ApiKeyService.ApiKeyDoc;
import org.elasticsearch.xpack.security.authc.ApiKeyService.CachedApiKeyHashResult;
import org.elasticsearch.xpack.security.authz.store.NativePrivilegeStore;
import org.elasticsearch.xpack.security.support.CacheInvalidatorRegistry;
import org.elasticsearch.xpack.security.support.FeatureNotEnabledException;
import org.elasticsearch.xpack.security.support.SecurityIndexManager;
import org.elasticsearch.xpack.security.test.SecurityMocks;
import org.junit.After;
import org.junit.Before;