### 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boolean property, as well as the `expiration` property that contains the UNIX timestamp past of which the key is no longer valid for authentication.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
for (RoleDescriptor descriptor : keyRoles) {
                builder.field(descriptor.getName(), (contentBuilder, params) -> descriptor.toXContent(contentBuilder, params, true));
            }
        }
        builder.endObject();
    }
    private void clearCache(InvalidateApiKeyResponse result, ActionListener<InvalidateApiKeyResponse> listener) {
        executeClearCacheRequest(
            result,
            listener,
            new ClearSecurityCacheRequest().cacheName("api_key").keys(result.getInvalidatedApiKeys().toArray(String[]::new))
        );
    }
    private void clearApiKeyDocCache(final BulkUpdateApiKeyResponse result, final ActionListener<BulkUpdateApiKeyResponse> listener) {
        executeClearCacheRequest(
            result,
            listener,
            new ClearSecurityCacheRequest().cacheName("api_key_doc").keys(result.getUpdated().toArray(String[]::new))
        );
    }
    private <T> void executeClearCacheRequest(T result, ActionListener<T> listener, ClearSecurityCacheRequest clearApiKeyCacheRequest) {
        executeAsyncWithOrigin(client, SECURITY_ORIGIN, ClearSecurityCacheAction.INSTANCE, clearApiKeyCacheRequest, new ActionListener<>() {
            @Override
            public void onResponse(ClearSecurityCacheResponse nodes) {
                listener.onResponse(result);
            }
            @Override
            public void onFailure(Exception e) {
                logger.error(() -> format("unable to clear API key cache [%s]", clearApiKeyCacheRequest.cacheName()), e);
                listener.onFailure(new ElasticsearchException("clearing the API key cache failed; please clear the caches manually", e));