### 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boolean property, as well as the `expiration` property that contains the UNIX timestamp past of which the key is no longer valid for authentication.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/core/src/test/java/org/elasticsearch/xpack/core/security/action/apikey/GetApiKeyRequestTests.java
getApiKeyRequest.writeTo(out);
            InputStreamStreamInput inputStreamStreamInput = new InputStreamStreamInput(new ByteArrayInputStream(outBuffer.toByteArray()));
            inputStreamStreamInput.setTransportVersion(randomVersionBetween(random(), TransportVersion.V_7_0_0, TransportVersion.V_7_3_0));
            GetApiKeyRequest requestFromInputStream = new GetApiKeyRequest(inputStreamStreamInput);
            assertThat(requestFromInputStream.getApiKeyId(), equalTo(getApiKeyRequest.getApiKeyId()));
            
            assertThat(requestFromInputStream.ownedByAuthenticatedUser(), is(false));
        }
        {
            final GetApiKeyRequest getApiKeyRequest = GetApiKeyRequest.builder()
                .apiKeyId(apiKeyId)
                .ownedByAuthenticatedUser(true)
                .withLimitedBy(randomBoolean())
                .build();
            ByteArrayOutputStream outBuffer = new ByteArrayOutputStream();
            OutputStreamStreamOutput out = new OutputStreamStreamOutput(outBuffer);
            out.setTransportVersion(randomVersionBetween(random(), TransportVersion.V_7_4_0, TransportVersion.V_8_4_0));
            getApiKeyRequest.writeTo(out);
            InputStreamStreamInput inputStreamStreamInput = new InputStreamStreamInput(new ByteArrayInputStream(outBuffer.toByteArray()));
            inputStreamStreamInput.setTransportVersion(randomVersionBetween(random(), TransportVersion.V_7_4_0, TransportVersion.V_8_4_0));
            GetApiKeyRequest requestFromInputStream = new GetApiKeyRequest(inputStreamStreamInput);
            assertThat(requestFromInputStream.getApiKeyId(), equalTo(getApiKeyRequest.getApiKeyId()));
            assertThat(requestFromInputStream.ownedByAuthenticatedUser(), is(true));
            
            assertThat(requestFromInputStream.withLimitedBy(), is(false));
        }
        {
            final GetApiKeyRequest getApiKeyRequest = GetApiKeyRequest.builder().apiKeyId(apiKeyId).withLimitedBy(randomBoolean()).build();
            ByteArrayOutputStream outBuffer = new ByteArrayOutputStream();
            OutputStreamStreamOutput out = new OutputStreamStreamOutput(outBuffer);