### 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boolean property, as well as the `expiration` property that contains the UNIX timestamp past of which the key is no longer valid for authentication.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
final AuthenticationResult<User> auth = tryAuthenticate(service, id, wrongKey, type);
        assertThat(auth.getStatus(), is(AuthenticationResult.Status.CONTINUE));
        assertThat(auth.getValue(), nullValue());
        assertThat(auth.getMessage(), containsString("invalid credentials for API key [" + id + "]"));
    }
    public void testAuthenticationFailureWithExpiredKey() throws Exception {
        final Settings settings = Settings.builder().put(XPackSettings.API_KEY_SERVICE_ENABLED_SETTING.getKey(), true).build();
        final ApiKeyService service = createApiKeyService(settings);
        final String id = randomAlphaOfLength(12);
        final String key = randomAlphaOfLength(16);
        final ApiKey.Type type = randomFrom(ApiKey.Type.values());
        mockKeyDocument(id, key, new User("hulk", "superuser"), null, false, Duration.ofSeconds(-1), null, type);
        final AuthenticationResult<User> auth = tryAuthenticate(service, id, key, type);
        assertThat(auth.getStatus(), is(AuthenticationResult.Status.CONTINUE));
        assertThat(auth.getValue(), nullValue());
        assertThat(auth.getMessage(), containsString("expired"));
    }
    /**
     * We cache valid and invalid responses. This test verifies that we handle these correctly.
     */
    public void testMixingValidAndInvalidCredentials() throws Exception {
        final Settings settings = Settings.builder().put(XPackSettings.API_KEY_SERVICE_ENABLED_SETTING.getKey(), true).build();
        final ApiKeyService service = createApiKeyService(settings);
        final String id = randomAlphaOfLength(12);
        final String realKey = randomAlphaOfLength(16);
        final User user, authUser;
        if (randomBoolean()) {
            user = new User("hulk", "superuser");
            authUser = new User("authenticated_user", "other");
        } else {