Add CCs -> Add Subscribers

Summary: I think this is the direction the language has been moving? Maybe this will train me that "CCs" are called "Subscribers". (I actually don't love this wording change, but consistency is good?)

Test Plan: {F163255}

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D9367

src/applications/differential/constants/DifferentialAction.php

@@ -113,7 +113,7 @@ final class DifferentialAction {
       self::ACTION_RECLAIM        => pht('Reclaim Revision'),
       self::ACTION_RESIGN         => pht('Resign as Reviewer'),
       self::ACTION_ADDREVIEWERS   => pht('Add Reviewers'),
-      self::ACTION_ADDCCS         => pht('Add CCs'),
+      self::ACTION_ADDCCS         => pht('Add Subscribers'),
       self::ACTION_CLOSE          => pht('Close Revision'),
       self::ACTION_CLAIM          => pht('Commandeer Revision'),
       self::ACTION_REOPEN         => pht('Reopen'),

src/applications/differential/view/DifferentialAddCommentView.php

@@ -91,7 +91,7 @@ final class DifferentialAddCommentView extends AphrontView {
           ->setDisableBehavior(true))
       ->appendChild(
         id(new AphrontFormTokenizerControl())
-          ->setLabel(pht('Add CCs'))
+          ->setLabel(pht('Add Subscribers'))
           ->setName('ccs')
           ->setControlID('add-ccs')
           ->setControlStyle($enable_ccs ? null : 'display: none')