### 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boolean property, as well as the `expiration` property that contains the UNIX timestamp past of which the key is no longer valid for authentication.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
if (filterOutExpiredKeys) {
            final BoolQueryBuilder expiredQuery = QueryBuilders.boolQuery();
            expiredQuery.should(QueryBuilders.rangeQuery("expiration_time").gt(clock.instant().toEpochMilli()));
            expiredQuery.should(QueryBuilders.boolQuery().mustNot(QueryBuilders.existsQuery("expiration_time")));
            boolQuery.filter(expiredQuery);
        }
        final Supplier<ThreadContext.StoredContext> supplier = client.threadPool().getThreadContext().newRestorableContext(false);
        try (ThreadContext.StoredContext ignore = client.threadPool().getThreadContext().stashWithOrigin(SECURITY_ORIGIN)) {
            final SearchRequest request = client.prepareSearch(SECURITY_MAIN_ALIAS)
                .setScroll(DEFAULT_KEEPALIVE_SETTING.get(settings))
                .setQuery(boolQuery)
                .setVersion(false)
                .setSize(1000)
                .setFetchSource(true)
                .request();
            securityIndex.checkIndexVersionThenExecute(
                listener::onFailure,
                () -> ScrollHelper.fetchAllByEntity(client, request, new ContextPreservingActionListener<>(supplier, listener), hitParser)
            );
        }
    }
    public static QueryBuilder filterForRealmNames(String[] realmNames) {
        if (realmNames == null || realmNames.length == 0) {
            return null;
        }
        if (realmNames.length == 1) {
            return QueryBuilders.termQuery("creator.realm", realmNames[0]);
        } else {
            final BoolQueryBuilder realmsQuery = QueryBuilders.boolQuery();
            for (String realmName : realmNames) {