Reimplement did_you_mean suggestions to keep behaviour accross rubies

Ruby 3.2 will introduce `Exception#detailed_message` and `did_you_mean`
has been already updated in Ruby 3.2 to use that.

The new behaviour means not changing the original `Exception#message`.
That means it is hard to get the previous error output, because
`Exception#detailed_message` includes not only `did_you_mean`
decorations, but also additional information like the exception class.

To fix this, I bring the old did_you_mean behavior into Thor, so that
the above changes do not affect us.

Author: deivid-rodriguez

lib/thor/error.rb

@@ -1,18 +1,28 @@
 class Thor
-  Correctable = if defined?(DidYouMean::SpellChecker) && defined?(DidYouMean::Correctable) # rubocop:disable Naming/ConstantName
-                  # In order to support versions of Ruby that don't have keyword
-                  # arguments, we need our own spell checker class that doesn't take key
-                  # words. Even though this code wouldn't be hit because of the check
-                  # above, it's still necessary because the interpreter would otherwise be
-                  # unable to parse the file.
-                  class NoKwargSpellChecker < DidYouMean::SpellChecker # :nodoc:
-                    def initialize(dictionary)
-                      @dictionary = dictionary
-                    end
-                  end
-
-                  DidYouMean::Correctable
-                end
+  if defined?(DidYouMean::SpellChecker)
+    # In order to support versions of Ruby that don't have keyword
+    # arguments, we need our own spell checker class that doesn't take key
+    # words. Even though this code wouldn't be hit because of the check
+    # above, it's still necessary because the interpreter would otherwise be
+    # unable to parse the file.
+    class NoKwargSpellChecker < DidYouMean::SpellChecker # :nodoc:
+      def initialize(dictionary)
+        @dictionary = dictionary
+      end
+    end
+  end
+
+  if defined?(DidYouMean::Correctable)
+    module Correctable
+      def to_s
+        super + DidYouMean.formatter.message_for(corrections)
+      end
+
+      def corrections
+        @corrections ||= self.class.const_get(:SpellChecker).new(self).corrections
+      end
+    end
+  end
 
   # Thor::Error is raised when it's caused by wrong usage of thor classes. Those
   # errors have their backtrace suppressed and are nicely shown to the user.
@@ -53,7 +63,7 @@ def initialize(command, all_commands, namespace)
       super(message)
     end
 
-    prepend Correctable if Correctable
+    prepend Correctable if defined?(Correctable)
   end
   UndefinedTaskError = UndefinedCommandError
 
@@ -92,24 +102,12 @@ def initialize(switches, unknown)
       super("Unknown switches #{unknown.map(&:inspect).join(', ')}")
     end
 
-    prepend Correctable if Correctable
+    prepend Correctable if defined?(Correctable)
   end
 
   class RequiredArgumentMissingError < InvocationError
   end
 
   class MalformattedArgumentError < InvocationError
   end
-
-  if Correctable
-    if DidYouMean.respond_to?(:correct_error)
-      DidYouMean.correct_error(Thor::UndefinedCommandError, UndefinedCommandError::SpellChecker)
-      DidYouMean.correct_error(Thor::UnknownArgumentError, UnknownArgumentError::SpellChecker)
-    else
-      DidYouMean::SPELL_CHECKERS.merge!(
-        'Thor::UndefinedCommandError' => UndefinedCommandError::SpellChecker,
-        'Thor::UnknownArgumentError' => UnknownArgumentError::SpellChecker
-      )
-    end
-  end
 end