Add current fame index from pry-stack_explorer

[rrosenblum]

pry-stack_explorer always lists the current frame number out of the total number of frames Frame number: 0/65. I would like to see the same thing in pry-byebug.

bundle exec rspec spec/rubocop/cop/style/method_missing_spec.rb:15
Run options: include {:focus=>true, :locations=>{"./spec/rubocop/cop/style/method_missing_spec.rb"=>[15]}}

Randomized with seed 22279

Frame number: 0/65

From: /~/work/rubocop/lib/rubocop/cop/style/method_missing.rb @ line 31 RuboCop::Cop::Style::MethodMissing#on_def:

    27: def on_def(node)
    28:   return unless node.method?(:method_missing)
    29: 
    30:   binding.pry
 => 31:   check(node)
    32: end

[1] pry(#<RuboCop::Cop::Style::MethodMissing>)> 
``