Make Layout/LeadingCommentSpace aware of #:nodoc

This PR makes `Layout/LeadingCommentSpace` aware of `#:nodoc`.

The following mention is the trigger.
https://twitter.com/kamipo/status/1421031611588485121

It seems that there was no definitive comment on whether to allow `#:nodoc:`.

- #277
- db79146

I've look RDoc doc's example of Ruby 3.0 and it looks to include leading comment space.

```ruby
module MyModule # :nodoc:
  class Input
  end
end

module OtherModule # :nodoc: all
  class Output
  end
end
```

https://docs.ruby-lang.org/en/3.0.0/RDoc/Markup.html#class-RDoc::Markup-label-Controlling+what+is+documented

I also considered making it an option for the presence or absence of
leading comment space in `#:nodoc:`, but I think it would be better to
consistent it that space is included when possible as the role of cop.

changelog/change_make_layout_leading_comment_space_aware_of_nodoc.md

@@ -0,0 +1 @@
+* [#9964](https://github.com/rubocop/rubocop/pull/9964): Make `Layout/LeadingCommentSpace` aware of `#:nodoc`. ([@koic][])

lib/rubocop/cop/layout/leading_comment_space.rb

@@ -57,7 +57,7 @@ class LeadingCommentSpace < Base
 
         def on_new_investigation
           processed_source.comments.each do |comment|
-            next unless /\A#+[^#\s=:+-]/.match?(comment.text)
+            next unless /\A#+[^#\s=+-]/.match?(comment.text)
             next if comment.loc.line == 1 && allowed_on_first_line?(comment)
             next if doxygen_comment_style?(comment)
             next if gemfile_ruby_comment?(comment)

spec/rubocop/cop/layout/leading_comment_space_spec.rb

@@ -135,12 +135,20 @@
     end
   end
 
-  it 'accepts rdoc syntax' do
-    expect_no_offenses(<<~RUBY)
-      #++
-      #--
-      #:nodoc:
-    RUBY
+  describe 'RDoc syntax' do
+    it 'does not register an offense when using `#++` or `#--`' do
+      expect_no_offenses(<<~RUBY)
+        #++
+        #--
+      RUBY
+    end
+
+    it 'registers an offense when starting `:`' do
+      expect_offense(<<~RUBY)
+        #:nodoc:
+        ^^^^^^^^ Missing space after `#`.
+      RUBY
+    end
   end
 
   it 'accepts sprockets directives' do