Fix unexpected non-local exits on Rubocop::AST::Node#parent_module_name

[sanfrecce-osaka]

With this PR, when Rubocop::AST::Node#parent_module_name_part is executed, it will no longer do non-local exits when a block is evaluated, and evaluating singleton_class or block in Rubocop::AST::Node#parent_module_name will behave as expected.
With this change, this PR aims to resolve the following issue.

rubocop/rubocop#5022

[marcandre]

Thanks for the PR.

I can only look at this more fully tomorrow, but this PR is not acceptable as is. The original intent was that parent_module_name_part could either return or yield a value (potentially nil). This PR now conflates both and result is over complicated for what it achieves.

Either parent_module_name_part should simply return a value, or else it needs to be modified in some way to achieve what we need.

[marcandre]

Closed in favor of #177

[marcandre]

See #197