Swap `expected` and `got` in `expect_offense` spec helper
Swap `expected` and `got` in `expect_offense` spec helper

I guess `expected` and `got` are inverses in the `expect_offense` spec helper.

For example:

```ruby
it 'registers an offense for wrong code' do
  expect_offense(<<-RUBY.strip_indent)
    something
    ^^^^^^^^^ It's wrong.
  RUBY
end
```

```
$ bundle exec rspec

(snip)

Failures:

  1) RuboCop::Cop::Lint::Loop registers an offense for wrong code
     Failure/Error: expect(expected_annotations.to_s).to eq(actual_annotations.to_s)

       expected: "something\n"
            got: "something\n^^^^^^^^^ It's wrong.\n"

       (compared using ==)

       Diff:
       @@ -1,2 +1,3 @@
        something
       +^^^^^^^^^ It's wrong.
     # ./lib/rubocop/rspec/expect_offense.rb:59:in `expect_offense'
     # ./spec/rubocop/cop/lint/loop_spec.rb:29:in `block (2 levels) in <top (required)>'

(snip)
```

The above spec expects to output `^^^^^^^^^ It's wrong.`.
But it is inverses in the spec failure message.

rrosenblum/rubocop,b-t-g/rubocop,deivid-rodriguez/rubocop,petehamilton/rubocop,panthomakos/rubocop,lumeet/rubocop,pocke/rubocop,jfelchner/rubocop,palkan/rubocop,smakagon/rubocop,petehamilton/rubocop,akihiro17/rubocop,haziqhafizuddin/rubocop,tejasbubane/rubocop,bbatsov/rubocop,tdeo/rubocop,rrosenblum/rubocop,panthomakos/rubocop,bbatsov/rubocop,maxjacobson/rubocop,tdeo/rubocop,jmks/rubocop,NobodysNightmare/rubocop,mikegee/rubocop,NobodysNightmare/rubocop,palkan/rubocop,bquorning/rubocop,maxjacobson/rubocop,palkan/rubocop,sue445/rubocop,scottmatthewman/rubocop,tdeo/rubocop,pocke/rubocop,jmks/rubocop,sue445/rubocop,iGEL/rubocop,meganemura/rubocop,bquorning/rubocop,tejasbubane/rubocop,urbanautomaton/rubocop,akihiro17/rubocop,scottmatthewman/rubocop,akihiro17/rubocop,mikegee/rubocop,alexcstark/rubocop,b-t-g/rubocop,vergenzt/rubocop,jfelchner/rubocop,rrosenblum/rubocop,jfelchner/rubocop,alexcstark/rubocop,maxjacobson/rubocop,sue445/rubocop,mikegee/rubocop,iGEL/rubocop,vergenzt/rubocop,jmks/rubocop,haziqhafizuddin/rubocop,meganemura/rubocop,deivid-rodriguez/rubocop,deivid-rodriguez/rubocop,vergenzt/rubocop,urbanautomaton/rubocop,panthomakos/rubocop,meganemura/rubocop,petehamilton/rubocop,tejasbubane/rubocop,smakagon/rubocop,bquorning/rubocop,lumeet/rubocop