Add C++ and Python API for Dolphin CTC models

[csukuangfj]

Support models from https://github.com/DataoceanAI/Dolphin

Note that only the CTC head is supported. We don't support its attention decoder.

Fixes #2083

CC @DataoceanAI @MXuer @hotbaby

Usage

Download a model from
https://github.com/k2-fsa/sherpa-onnx/releases/tag/asr-models

• sherpa-onnx-dolphin-base-ctc-multi-lang-int8-2025-04-02.tar.bz2
• sherpa-onnx-dolphin-base-ctc-multi-lang-2025-04-02.tar.bz2
• sherpa-onnx-dolphin-small-ctc-multi-lang-int8-2025-04-02.tar.bz2
• sherpa-onnx-dolphin-small-ctc-multi-lang-2025-04-02.tar.bz2

After building sherpa-onnx, run

build/bin/sherpa-onnx-offline
  --dolphin-model=./sherpa-onnx-dolphin-base-ctc-multi-lang-int8-2025-04-02/model.int8.onnx \
  --tokens=./sherpa-onnx-dolphin-base-ctc-multi-lang-int8-2025-04-02/tokens.txt \
  ./sherpa-onnx-dolphin-base-ctc-multi-lang-int8-2025-04-02/test_wavs/0.wav

[MXuer]

感谢军哥。

[hotbaby]

感谢军哥。

[Geministudents]

sherpa_onnx.OfflineRecognizer.from_dolphin_ctc中没有langue参数，dolphin官方的region_sym参数也没有，这样的话会不会对效果产生影响呢，比如官方转写闽南语需要这两个参数：lang_sym="zh", region_sym="TW"

[csukuangfj]

我们不需要指定，也不支持指定