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

lib/topic_query_sql.rb

@@ -14,7 +14,7 @@ module TopicQuerySQL
       -"CASE WHEN categories.id = #{SiteSetting.uncategorized_category_id.to_i} THEN '' ELSE categories.name END #{dir}"
     end
 
-    # If you've clearned the pin, use bumped_at, otherwise put it at the top
+    # If you've cleared the pin, use bumped_at, otherwise put it at the top
     def order_with_pinned_sql
       -"CASE
         WHEN (COALESCE(topics.pinned_at, '#{lowest_date}') > COALESCE(tu.cleared_pinned_at, '#{lowest_date}'))
@@ -23,7 +23,7 @@ module TopicQuerySQL
        END DESC"
     end
 
-    # If you've clearned the pin, use bumped_at, otherwise put it at the top
+    # If you've cleared the pin, use bumped_at, otherwise put it at the top
     def order_nocategory_with_pinned_sql
       -"CASE
         WHEN topics.pinned_globally