Add feature flag for contact sharing.

Signal/src/ViewControllers/ConversationView/ConversationViewController.m

@@ -3615,8 +3615,10 @@ typedef enum : NSUInteger {
     [gifAction setValue:gifImage forKey:@"image"];
     [actionSheetController addAction:gifAction];
 
-    UIAlertAction *chooseContactAction = [UIAlertAction
-        actionWithTitle:NSLocalizedString(@"ATTACHMENT_MENU_CONTACT_BUTTON", @"attachment menu option to send contact")
+    if (kIsSendingContactSharesEnabled) {
+        UIAlertAction *chooseContactAction =
+            [UIAlertAction actionWithTitle:NSLocalizedString(@"ATTACHMENT_MENU_CONTACT_BUTTON",
+                                               @"attachment menu option to send contact")
                                      style:UIAlertActionStyleDefault
                                    handler:^(UIAlertAction *_Nonnull action) {
                                        [self chooseContactForSending];
@@ -3626,6 +3628,7 @@ typedef enum : NSUInteger {
         OWSAssert(takeMediaImage);
         [chooseContactAction setValue:chooseContactImage forKey:@"image"];
         [actionSheetController addAction:chooseContactAction];
+    }
 
     [self dismissKeyBoard];
     [self presentViewController:actionSheetController animated:true completion:nil];