Give Drydock resources a proper expiry mechanism

Summary:
Fixes T6569. This implements an expiry mechanism for Drydock resources which parallels the mechanism for leases.

A few things are missing that we'll probably need in the future:

  - An "EXPIRES" command to update the expiration time. This would let resources be permanent while leased, then expire after, say, 24 hours without any leases.
  - A callback like `shouldActuallyExpireRightNow()` for resources and leases that lets them decide not to expire at the last second.
  - A callback like `didAcquireLease()` for resource blueprints, to parallel `didReleaseLease()`, letting them clear or extend their timer.

However, this stuff would mostly just let us tune behaviors, not really open up new capabilities.

Test Plan: Changed host resources to expire after 60 seconds, leased one, saw it vanish 60 seconds later.

Reviewers: hach-que, chad

Reviewed By: chad

Maniphest Tasks: T6569

Differential Revision: https://secure.phabricator.com/D14176

src/applications/drydock/controller/DrydockResourceViewController.php

@@ -116,6 +116,14 @@ final class DrydockResourceViewController extends DrydockResourceController {
       pht('Status'),
       $status);
 
+    $until = $resource->getUntil();
+    if ($until) {
+      $until_display = phabricator_datetime($until, $viewer);
+    } else {
+      $until_display = phutil_tag('em', array(), pht('Never'));
+    }
+    $view->addProperty(pht('Expires'), $until_display);
+
     $view->addProperty(
       pht('Resource Type'),
       $resource->getType());