### 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boolean property, as well as the `expiration` property that contains the UNIX timestamp past of which the key is no longer valid for authentication.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
long creationTime,
            long expirationTime,
            Boolean invalidated,
            String hash,
            @Nullable String name,
            int version,
            BytesReference roleDescriptorsBytes,
            BytesReference limitedByRoleDescriptorsBytes,
            Map<String, Object> creator,
            @Nullable BytesReference metadataFlattened
        ) {
            this.docType = docType;
            if (type == null) {
                logger.trace("API key document with [null] type defaults to [rest] type");
                this.type = ApiKey.Type.REST;
            } else {
                this.type = type;
            }
            this.creationTime = creationTime;
            this.expirationTime = expirationTime;
            this.invalidated = invalidated;
            this.hash = hash;
            this.name = name;
            this.version = version;
            this.roleDescriptorsBytes = roleDescriptorsBytes;
            this.limitedByRoleDescriptorsBytes = limitedByRoleDescriptorsBytes;
            this.creator = creator;
            this.metadataFlattened = NULL_BYTES.equals(metadataFlattened) ? null : metadataFlattened;
        }
        public CachedApiKeyDoc toCachedApiKeyDoc() {