### 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boolean property, as well as the `expiration` property that contains the UNIX timestamp past of which the key is no longer valid for authentication.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
out.setTransportVersion(randomVersionBetween(random(), TransportVersion.V_8_5_0, TransportVersion.current()));
            getApiKeyRequest.writeTo(out);
            InputStreamStreamInput inputStreamStreamInput = new InputStreamStreamInput(new ByteArrayInputStream(outBuffer.toByteArray()));
            inputStreamStreamInput.setTransportVersion(
                randomVersionBetween(random(), TransportVersion.V_8_5_0, TransportVersion.current())
            );
            GetApiKeyRequest requestFromInputStream = new GetApiKeyRequest(inputStreamStreamInput);
            assertThat(requestFromInputStream, equalTo(getApiKeyRequest));
        }
    }
    public void testEmptyStringsAreCoercedToNull() {
        Supplier<String> randomBlankString = () -> " ".repeat(randomIntBetween(0, 5));
        final GetApiKeyRequest request = GetApiKeyRequest.builder()
            .realmName(randomBlankString.get())
            .userName(randomBlankString.get())
            .apiKeyId(randomBlankString.get())
            .apiKeyName(randomBlankString.get())
            .ownedByAuthenticatedUser(randomBoolean())
            .withLimitedBy(randomBoolean())
            .build();
        assertThat(request.getRealmName(), nullValue());
        assertThat(request.getUserName(), nullValue());
        assertThat(request.getApiKeyId(), nullValue());
        assertThat(request.getApiKeyName(), nullValue());
    }
    private static String randomNullOrEmptyString() {
        return randomBoolean() ? "" : null;
    }
}