### 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boolean property, as well as the `expiration` property that contains the UNIX timestamp past of which the key is no longer valid for authentication.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
private ApiKeyService createApiKeyService(Settings baseSettings) {
        final Settings settings = Settings.builder()
            .put(XPackSettings.API_KEY_SERVICE_ENABLED_SETTING.getKey(), true)
            .put(baseSettings)
            .build();
        final ClusterSettings clusterSettings = new ClusterSettings(
            settings,
            Sets.union(ClusterSettings.BUILT_IN_CLUSTER_SETTINGS, Set.of(ApiKeyService.DELETE_RETENTION_PERIOD))
        );
        final ApiKeyService service = new ApiKeyService(
            settings,
            clock,
            client,
            securityIndex,
            ClusterServiceUtils.createClusterService(threadPool, clusterSettings),
            cacheInvalidatorRegistry,
            threadPool
        );
        if ("0s".equals(settings.get(ApiKeyService.CACHE_TTL_SETTING.getKey()))) {
            verify(cacheInvalidatorRegistry, never()).registerCacheInvalidator(eq("api_key"), any());
        } else {
            verify(cacheInvalidatorRegistry).registerCacheInvalidator(eq("api_key"), any());
        }
        return service;
    }
    private Map<String, Object> buildApiKeySourceDoc(char[] hash) {
        Map<String, Object> sourceMap = new HashMap<>();
        sourceMap.put("doc_type", "api_key");
        if (randomBoolean()) {
            sourceMap.put("type", randomFrom(ApiKey.Type.values()).value());