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/jobs/bulk_invite_spec.rb

@@ -81,7 +81,7 @@ describe Jobs::BulkInvite do
       expect(existing_user.reload.groups).to eq([group1])
     end
 
-    it 'can create staged users and prepulate user fields' do
+    it 'can create staged users and prepopulate user fields' do
       user_field = Fabricate(:user_field, name: "Location")
       user_field_color = Fabricate(:user_field, field_type: "dropdown", name: "Color")
       user_field_color.user_field_options.create!(value: "Red")

spec/jobs/jobs_spec.rb

@@ -42,7 +42,7 @@ describe Jobs do
         end
         expect(jobs.length).to eq(2)
 
-        # Failed transation
+        # Failed transaction
         ActiveRecord::Base.transaction do
           Jobs.enqueue(:process_post, post_id: 1)
           raise ActiveRecord::Rollback