Use the new Autocorrection API

The autocorrection API was changed in Rubocop v0.87.0 (pull request rubocop/rubocop#7868).

Here, I change the superclass of `RuboCop::Cop::RSpec::Cop` from
`::RuboCop::Cop::Cop` to `::RuboCop::Cop::Base`.

This has a few consequences:

- Our `#message` methods get called with a different argument than
  before. It *can* be customized by defining a `#callback_argument`
  method, but I think it is clearer to avoid callbacks altogether.
- Our `#autocorrect` methods don't get called anymore. Instead, we
  extend `Autocorrector`, and the `corrector` is being yielded when
  calling `#add_offense`, so the code is mostly moved in there. For some
  cases, this means that some code can be removed, which is nice. For
  some cases, it means that the methods get too long, or the code
  complexity gets too high, and in those cases I chose to just call out
  to an `#autocorrect` method anyway, but of course passing the
  `corrector` and any usable local variables along.

This also means we bump the dependency of RuboCop quite a bit, from
'>= 0.68.1' to '>= 0.87.0'.

.rubocop_todo.yml

@@ -14,4 +14,4 @@ InternalAffairs/MethodNameEqual:
 # Offense count: 1
 # Configuration parameters: CountComments.
 Metrics/ClassLength:
-  Max: 104
+  Max: 106

rubocop-rspec_rails.gemspec

@@ -36,7 +36,7 @@ Gem::Specification.new do |spec|
     'documentation_uri' => 'https://rubocop-rspec.readthedocs.io/'
   }
 
-  spec.add_runtime_dependency 'rubocop', '>= 0.68.1'
+  spec.add_runtime_dependency 'rubocop', '>= 0.87.0'
 
   spec.add_development_dependency 'rack'
   spec.add_development_dependency 'rake'

tasks/cops_documentation.rake

@@ -40,7 +40,7 @@ task generate_cops_documentation: :yard_for_generate_documentation do
     ]
     config = config.for_cop(cop)
     safe_auto_correct = config.fetch('SafeAutoCorrect', true)
-    autocorrect = if cop.new.support_autocorrect?
+    autocorrect = if cop.support_autocorrect?
                     "Yes #{'(Unsafe)' unless safe_auto_correct}"
                   else
                     'No'