Render timezones in event reminder mail, and render them more nicely

Summary:
Fixes T12356.

  - In this mail, we currently render "6:00 AM". Instead, render "6:00 AM (PDT)" or similar. This is consistent with times in other modern Transaction mail.
  - Previously, we would render "UTC-7". Render "PDT" instead. For obscure zones with no known timezone abbreviation, fall back to "UTC-7".

Test Plan:
  - Used `bin/calendar notify --minutes X` to trigger notifications, read email bodies.
  - Used this script to list all `T` values and checked them for sanity:

```lang=php
<?php

$now = new DateTime();

$locales = DateTimeZone::listIdentifiers();
foreach ($locales as $locale) {
  $zone = new DateTimeZone($locale);
  $now->setTimeZone($zone);

  printf(
    "%s (%s)\n",
    $locale,
    $now->format('T'));
}
```

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T12356

Differential Revision: https://secure.phabricator.com/D17646

src/__phutil_library_map__.php

@@ -4692,6 +4692,7 @@ phutil_register_library_map(array(
     'javelin_tag' => 'infrastructure/javelin/markup.php',
     'phabricator_date' => 'view/viewutils.php',
     'phabricator_datetime' => 'view/viewutils.php',
+    'phabricator_datetimezone' => 'view/viewutils.php',
     'phabricator_form' => 'infrastructure/javelin/markup.php',
     'phabricator_format_local_time' => 'view/viewutils.php',
     'phabricator_relative_date' => 'view/viewutils.php',

src/applications/calendar/notifications/PhabricatorCalendarEventNotificationView.php

@@ -58,4 +58,12 @@ final class PhabricatorCalendarEventNotificationView
     return phabricator_datetime($epoch, $viewer);
   }
 
+  public function getDisplayTimeWithTimezone() {
+    $viewer = $this->getViewer();
+
+    $epoch = $this->getEpoch();
+    return phabricator_datetimezone($epoch, $viewer);
+  }
+
+
 }

src/applications/calendar/notifications/PhabricatorCalendarNotificationEngine.php

@@ -268,7 +268,7 @@ final class PhabricatorCalendarNotificationEngine
           '%s is starting in %s minute(s), at %s.',
           $event->getEvent()->getName(),
           $event->getDisplayMinutes(),
-          $event->getDisplayTime()));
+          $event->getDisplayTimeWithTimezone()));
 
       $body->addLinkSection(
         pht('EVENT DETAIL'),

src/applications/transactions/storage/PhabricatorModularTransactionType.php

@@ -234,22 +234,15 @@ abstract class PhabricatorModularTransactionType
 
     if ($all_day) {
       $display = phabricator_date($epoch, $viewer);
-    } else {
-      $display = phabricator_datetime($epoch, $viewer);
-
+    } else if ($this->isRenderingTargetExternal()) {
       // When rendering to text, we explicitly render the offset from UTC to
       // provide context to the date: the mail may be generating with the
       // server's settings, or the user may later refer back to it after
       // changing timezones.
 
-      if ($this->isRenderingTargetExternal()) {
-        $offset = $viewer->getTimeZoneOffsetInHours();
-        if ($offset >= 0) {
-          $display = pht('%s (UTC+%d)', $display, $offset);
-        } else {
-          $display = pht('%s (UTC-%d)', $display, abs($offset));
-        }
-      }
+      $display = phabricator_datetimezone($epoch, $viewer);
+    } else {
+      $display = phabricator_datetime($epoch, $viewer);
     }
 
     return $this->renderValue($display);

src/view/viewutils.php

@@ -48,6 +48,24 @@ function phabricator_datetime($epoch, $user) {
       $user->getUserSetting($time_key)));
 }
 
+function phabricator_datetimezone($epoch, $user) {
+  $datetime = phabricator_datetime($epoch, $user);
+  $timezone = phabricator_format_local_time($epoch, $user, 'T');
+
+  // Some obscure timezones just render as "+03" or "-09". Make these render
+  // as "UTC+3" instead.
+  if (preg_match('/^[+-]/', $timezone)) {
+    $timezone = (int)trim($timezone, '+');
+    if ($timezone < 0) {
+      $timezone = pht('UTC-%s', $timezone);
+    } else {
+      $timezone = pht('UTC+%s', $timezone);
+    }
+  }
+
+  return pht('%s (%s)', $datetime, $timezone);
+}
+
 /**
  * This function does not usually need to be called directly. Instead, call
  * @{function:phabricator_date}, @{function:phabricator_time}, or