DEV: Correct typos and spelling mistakes (#12812)

Over the years we accrued many spelling mistakes in the code base. 

This PR attempts to fix spelling mistakes and typos in all areas of the code that are extremely safe to change 

- comments
- test descriptions
- other low risk areas

spec/models/notification_spec.rb

@@ -298,7 +298,7 @@ describe Notification do
       expect(user.unread_notifications).to eq(0)
       expect(user.total_unread_notifications).to eq(3)
       # NOTE: because of deprecation this will be equal to unread_high_priority_notifications,
-      #       to be remonved in 2.5
+      #       to be removed in 2.5
       expect(user.unread_private_messages).to eq(2)
       expect(user.unread_high_priority_notifications).to eq(2)
     end