whisper : add grammar-based sampling (#1229)

* whisper : add grammar-based sampling

* build : fix after master merge

* command : fix exception when recognizing the command

* whisper : fine-tuning grammar functionality

* command : grammar-related improvements

- option to read grammar from file
- add sample grammars for colors and chess moves
- fine-tune the performance further

* grammars : add assistant + update comments

* command : enable beam-search, add "no_timestamps", add "context", add p

* whisper : remove comment

---------

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

examples/CMakeLists.txt

@@ -23,6 +23,7 @@ add_library(${TARGET} STATIC
     common.cpp
     common-ggml.h
     common-ggml.cpp
+    grammar-parser.cpp
     )
 
 include(DefaultTargetOptions)