### 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boolean property, as well as the `expiration` property that contains the UNIX timestamp past of which the key is no longer valid for authentication.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/test/java/org/elasticsearch/xpack/security/authc/ApiKeyServiceTests.java
service.validateApiKeyCredentials(
            apiKeyId,
            apiKeyDoc,
            getApiKeyCredentials(apiKeyId, randomAlphaOfLength(15), apiKeyDoc.type),
            Clock.systemUTC(),
            future
        );
        result = future.get();
        assertNotNull(result);
        assertFalse(result.isAuthenticated());
        
        assertNull(service.getApiKeyAuthCache().get(apiKeyId));
    }
    @SuppressWarnings("unchecked")
    public void testParseRoleDescriptorsMap() throws Exception {
        final String apiKeyId = randomAlphaOfLength(12);
        final NativePrivilegeStore privilegesStore = mock(NativePrivilegeStore.class);
        doAnswer(i -> {
            assertThat(i.getArguments().length, equalTo(3));
            final Object arg2 = i.getArguments()[2];
            assertThat(arg2, instanceOf(ActionListener.class));
            ActionListener<Collection<ApplicationPrivilege>> listener = (ActionListener<Collection<ApplicationPrivilege>>) arg2;
            listener.onResponse(Collections.emptyList());
            return null;
        }).when(privilegesStore).getPrivileges(any(Collection.class), any(Collection.class), anyActionListener());
        ApiKeyService service = createApiKeyService(Settings.EMPTY);
        assertThat(service.parseRoleDescriptors(apiKeyId, null, randomApiKeyRoleType()), nullValue());
        assertThat(service.parseRoleDescriptors(apiKeyId, Collections.emptyMap(), randomApiKeyRoleType()), emptyIterable());
        final RoleDescriptor roleARoleDescriptor = new RoleDescriptor(
            "a role",