Fix various "strlen(null)" PHP 8.1 issues on "bin/phd" and "bin/drydock" pathways

Summary: Ref T13676. Ref T13588. Fix some issues that prevent "bin/phd" and "bin/drydock" from executing under PHP 8.1, broadly because `null` is being passed to `strlen()`.

Test Plan: Ran `bin/phd debug task` and `bin/drydock ...` under PHP 8.1.

Subscribers: PHID-OPKG-gm6ozazyms6q6i22gyam

Maniphest Tasks: T13676, T13588

Differential Revision: https://secure.phabricator.com/D21795

src/applications/auth/provider/PhabricatorOAuth1AuthProvider.php

···
     $config = $this->getProviderConfig();
     $adapter->setConsumerKey($config->getProperty(self::PROPERTY_CONSUMER_KEY));
     $secret = $config->getProperty(self::PROPERTY_CONSUMER_SECRET);
-    if (strlen($secret)) {
+    if (phutil_nonempty_string($secret)) {
       $adapter->setConsumerSecret(new PhutilOpaqueEnvelope($secret));
     }
     $adapter->setCallbackURI(PhabricatorEnv::getURI($this->getLoginURI()));

src/applications/cache/management/PhabricatorCacheManagementPurgeWorkflow.php

···
     $is_all = $args->getArg('all');
     $key_list = $args->getArg('caches');
 
-    if ($is_all && strlen($key_list)) {
+    if ($is_all && phutil_nonempty_string($key_list)) {
       throw new PhutilArgumentUsageException(
         pht(
           'Specify either "--all" or "--caches", not both.'));
-    } else if (!$is_all && !strlen($key_list)) {
+    } else if (!$is_all && !phutil_nonempty_string($key_list)) {
       throw new PhutilArgumentUsageException(
         pht(
           'Select caches to purge with "--all" or "--caches". Available '.

src/applications/daemon/event/PhabricatorDaemonEventListener.php

···
     // TODO: This is a bit awkward for historical reasons, clean it up after
     // removing Conduit.
     $message = $event->getValue('message');
+
     $context = $event->getValue('context');
-    if (strlen($context) && $context !== $message) {
-      $message = "({$context}) {$message}";
+    if (phutil_nonempty_scalar($context)) {
+      if ($context !== $message) {
+        $message = "({$context}) {$message}";
+      }
     }
 
     $type = $event->getValue('type');

src/applications/drydock/management/DrydockManagementLeaseWorkflow.php

···
     }
 
     $until = $args->getArg('until');
-    if (strlen($until)) {
+    if (phutil_nonempty_string($until)) {
       $until = strtotime($until);
       if ($until <= 0) {
         throw new PhutilArgumentUsageException(
···
     }
 
     $attributes_file = $args->getArg('attributes');
-    if (strlen($attributes_file)) {
+    if (phutil_nonempty_string($attributes_file)) {
       if ($attributes_file == '-') {
         echo tsprintf(
           "%s\n",

src/applications/policy/query/PhabricatorPolicyQuery.php

···
   }
 
   public static function isSpecialPolicy($identifier) {
+    if ($identifier === null) {
+      return true;
+    }
+
     if (self::isObjectPolicy($identifier)) {
       return true;
     }

src/applications/repository/storage/PhabricatorRepository.php

···
 
   public function getMonogram() {
     $callsign = $this->getCallsign();
-    if (strlen($callsign)) {
+    if (phutil_nonempty_string($callsign)) {
       return "r{$callsign}";
     }
 

src/applications/transactions/storage/PhabricatorApplicationTransaction.php

···
           }
 
           if (!is_array($old)) {
-            if (!strlen($old)) {
+            if ($old === '' || $old === null) {
               return true;
             }
 

src/infrastructure/customfield/standard/PhabricatorStandardCustomFieldPHIDs.php

···
   }
 
   protected function decodeValue($value) {
+    if ($value === null) {
+      return array();
+    }
+
     $value = json_decode($value);
     if (!is_array($value)) {
       $value = array();

src/infrastructure/query/policy/PhabricatorCursorPagedPolicyAwareQuery.php

···
 
     $this->setLimit($limit + 1);
 
-    if (strlen($pager->getAfterID())) {
+    if (phutil_nonempty_string($pager->getAfterID())) {
       $this->setExternalCursorString($pager->getAfterID());
     } else if ($pager->getBeforeID()) {
       $this->setExternalCursorString($pager->getBeforeID());