Process non-self singleton classes

[k0kubun]

To avoid deep indentation while still using private and skipping def self., I sometimes declare a class and define singleton methods on it with class << Example = Class.new. I'd like Solargraph to process its children.

class << Example = Class.new
  def foo
    bar
  end

  private

  def bar
    "example"
  end
end

The current SclassNodes supports only class << self, so I extended it to handle the above CDECL case as well as CONST case, .e.g. class << Example.

[k0kubun]

@castwide Any thoughts? I'll close this if you're uncomfortable with supporting this feature. I use this syntax in many of my projects and it's been painful whenever solargraph without this is installed.

[castwide]

I've been meaning to support this for a while. Thanks for taking care of it.