### 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boolean property, as well as the `expiration` property that contains the UNIX timestamp past of which the key is no longer valid for authentication.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
@Override
                public void invalidate(Collection<String> keys) {
                    if (apiKeyDocCache != null) {
                        apiKeyDocCache.invalidate(keys);
                    }
                }
                @Override
                public void invalidateAll() {
                    if (apiKeyDocCache != null) {
                        apiKeyDocCache.invalidateAll();
                    }
                }
            });
        } else {
            this.apiKeyAuthCache = null;
            this.apiKeyDocCache = null;
        }
    }
    /**
     * Asynchronously creates a new API key based off of the request and authentication
     * @param authentication the authentication that this api key should be based off of
     * @param request the request to create the api key included any permission restrictions
     * @param userRoleDescriptors the user's actual roles that we always enforce
     * @param listener the listener that will be used to notify of completion
     */
    public void createApiKey(
        Authentication authentication,
        AbstractCreateApiKeyRequest request,
        Set<RoleDescriptor> userRoleDescriptors,
        ActionListener<CreateApiKeyResponse> listener