ruby : fix bindings (#2484)

ruby : fix bindings (#2484)

* Improve Rakefile

* Remove intermediate files

* Remove unnecessary manipulations from extconf.rb

* Add README and LINCENSE to source files

* Manage ext source files using YAML file

* Use extsources.yaml to include files into gem package file

* Add git-managed source files to build dependency

* Add test task

* Download model for test if not exists

* Add test for build

* Ignore gem package directory

* Enable GitHub action for Ruby binding

* Fix model name

* Build lib file for test

* Use extension for each platform

* Use extension for each platform on testing

* Move built lib file rather than copy

* Add intermediate files to clean targets