DocstringParser warnings improvements

[notEthan]

Several improvements:

• Warnings about unknown params are skipped when the param is delegated to another method, determined by the param tag being a reference and the method taking a splat argument.
• param reference tags' names are used when possible.
• DocstringParser warnings include parser.object in the message - having the file/line number as it does now is sufficient, but jumping to the method name or class name can be simpler

The first one was what motivated this work, I wanted to get rid of warnings about delegated params. The rest were changes I made along the way.

Completed Tasks

• I have read the Contributing Guide.
• The pull request is complete (implemented / written).
• Git commits have been cleaned up (squash WIP / revert commits).
• I wrote tests and ran bundle exec rake locally (if code is attached to PR).

[notEthan]

This is incomplete, it should handle argument forwarding with def foo(...) as well as splat. currently YARD::Handlers::Ruby::MethodHandler does not add a parameter for a ... param, I'm having a look at what might be done with that. I could add a param named ... there (haven't explored what else that might affect), but I am thinking maybe better to just drop the check for a splat/forwarding param here, not warn about unknown params that are (see ...) refs at all, trusting that they are handled.

[Skipants]

I hope you don't mind some random reviewing your PR. I'm using Yard a lot lately and am invested in helping out.

[Skipants]

You can flatten down this if and improve readability IMO by using .filter_map to iterate here. Consider:

param_tags = parser.tags.filter_map do |tag|
  next unless tag.tag_name == "param"
  next tag if !tag.is_a?(Tags::RefTagList) || tag.name
  
  tag.tags unless CodeObjects::Proxy === tag.owner
end

filter_map is Ruby 2.7+ and I'm not sure about Yard's current minimum Ruby version, so if it's lower you can use map{ ... }.compact instead.