ruby : add VAD support, migration to Ruby's newer API (#3197)

ruby : add VAD support, migration to Ruby's newer API (#3197)

* Add VAD models

* Extract function to normalize model path from ruby_whisper_initialize()

* Define ruby_whisper_vad_params struct

* Add VAD-related features to Whisper::Params

* Add tests for VAD-related features

* Define Whisper::VADParams

* Add Whisper::VAD::Params attributes

* Add test suite for VAD::Params

* Make older test to follow namespace change

* Add test for transcription with VAD

* Add assertion for test_vad_params

* Add signatures for VAD-related methods

* Define VAD::Params#==

* Add test for VAD::Params#==

* Fix Params#vad_params

* Add test for Params#vad_params

* Fix signature of Params#vad_params

* Use macro to define VAD::Params params

* Define VAD::Params#initialize

* Add tests for VAD::Params#initialize

* Add signature for VAD::Params.new

* Add documentation on VAD in README

* Wrap register_callbask in prepare_transcription for clear meanings

* Set whisper_params.vad_params just before transcription

* Don't touch NULL

* Define ruby_whisper_params_type

* Use TypedData_XXX for ruby_whisper_params instead of Data_XXX

* Remove unused functions

* Define rb_whisper_model_data_type

* Use TypedData_XXX for ruby_whisper_model instead of Data_XXX

* Define ruby_whisper_segment_type

* Use TypedData_XXX for ruby_whisper_segment instead of Data_XXX

* Define ruby_whisper_type

* Use TypedData_XXX for ruby_whisper instead of Data_XXX

* Qualify with const