Add new InternalAffairs/MethodNameEndWith cop

[nobuyo]

Added new cop inspired by #10594 (comment).

This cop checks potentially usage of method identifier predicates instead of method_name.to_s.end_with?.

example

# bad
node.method_name.to_s.end_with?('=')

# good
node.assignment_method?

# bad
node.method_name.to_s.end_with?('?')

# good
node.predicate_method?

# bad
node.method_name.to_s.end_with?('!')

# good
node.bang_method?

I also did some refactoring of existing cops to conform to this cop.

---

Before submitting the PR make sure the following are checked:

• The PR relates to only one subject with a clear title and description in grammatically correct, complete sentences.
• Wrote good commit messages.
• Commit message starts with [Fix #issue-number] (if the related issue exists).
• Feature branch is up-to-date with master (if not - rebase it).
• Squashed related commits together.
• Added tests.
• Ran bundle exec rake default. It executes all tests and runs RuboCop on its own code.
• Added an entry (file) to the changelog folder named {change_type}_{change_description}.md if the new code introduces user-observable changes. See changelog entry format for details.

[koic]

Using constant instead of method will reduce unnecessary object creation.

[koic]

This is an internal private cop for development. So changelog entry may not be required.

[koic]

It can probably narrow the scope of these disable comments. The positions will be clearer.

diff --git a/lib/rubocop/cop/naming/predicate_name.rb b/lib/rubocop/cop/naming/predicate_name.rb
index 740166125..fbbad0f26 100644
--- a/lib/rubocop/cop/naming/predicate_name.rb
+++ b/lib/rubocop/cop/naming/predicate_name.rb
@@ -66,12 +66,11 @@ module RuboCop

         private

-        # rubocop:todo InternalAffairs/MethodNameEndWith
         def allowed_method_name?(method_name, prefix)
           !(method_name.start_with?(prefix) && # cheap check to avoid allocating Regexp
               method_name.match?(/^#{prefix}[^0-9]/)) ||
             method_name == expected_name(method_name, prefix) ||
-            method_name.end_with?('=') ||
+            method_name.end_with?('=') || # rubocop:todo InternalAffairs/MethodNameEndWith
             allowed_method?(method_name)
         end

@@ -81,10 +80,10 @@ module RuboCop
                      else
                        method_name.dup
                      end
-          new_name << '?' unless method_name.end_with?('?')
+          new_name << '?' unless method_name.end_with?('?') # rubocop:todo InternalAffairs/MethodNameEndWith
+
           new_name
         end
-        # rubocop:enable InternalAffairs/MethodNameEndWith

         def message(method_name, new_name)
           "Rename `#{method_name}` to `#{new_name}`."

[koic]

And rubocop:disable may be preferable to rubocop:todo if there is no fix.

[nobuyo]

It's not impossible, but these methods are mostly concerned with method_name, and it seemed a bit off to change them to receive node as argument to conform to this cop.
I didn't know if I should refactor it here, so compromised with rubocop:todo.

[nobuyo]

Thank you so much! I'll start fixing them.

[nobuyo]

I've fixed and updated except for #10600 (comment).

[koic]

Thanks!