whisper : add support for --carry-initial-prompt (#3395)

* Add support for --carry-initial-prompt

* PR fixes for ruby and go

* Refactoring for readability

* WIP 1

* WIP 2

* PR fixes

* More PR fixes

* PR fix

* Further simplification

* d'oh

* One more logic fix

* Update src/whisper.cpp

Co-authored-by: Georgi Gerganov <ggerganov@gmail.com>

* Truncate prompt_past0 upon initialization

* Slight simplification

---------

Co-authored-by: Georgi Gerganov <ggerganov@gmail.com>

bindings/ruby/test/test_params.rb

@@ -16,6 +16,7 @@ class TestParams < TestBase
     :max_len,
     :split_on_word,
     :initial_prompt,
+    :carry_initial_prompt,
     :diarize,
     :offset,
     :duration,
@@ -119,6 +120,13 @@ class TestParams < TestBase
     assert !@params.print_timestamps
   end
 
+  def test_carry_initial_prompt
+    @params.carry_initial_prompt = true
+    assert @params.carry_initial_prompt
+    @params.carry_initial_prompt = false
+    assert !@params.carry_initial_prompt
+  end
+
   def test_suppress_blank
     @params.suppress_blank = true
     assert @params.suppress_blank