Build sherpa-onnx as a single shared library (#1078)

When `-D BUILD_SHARED_LIBS=ON` is passed to `cmake`, it builds a single shared library.

Specifically, 

- For C APIs, it builds `libsherpa-onnx-c-api.so`
- For Python APIs, it builds `_sherpa_onnx.cpython-xx-xx.so`
- For Kotlin and Java APIs, it builds `libsherpa-onnx-jni.so`

There is no `libsherpa-onnx-core.so` any longer.

Note it affects only shared libraries.

.github/workflows/test-python-offline-websocket-server.yaml

@@ -57,7 +57,7 @@ jobs:
       - name: Install Python dependencies
         shell: bash
         run: |
-          python3 -m pip install --upgrade pip numpy pypinyin sentencepiece
+          python3 -m pip install --upgrade pip numpy pypinyin sentencepiece setuptools wheel
 
       - name: Install sherpa-onnx
         shell: bash
@@ -66,7 +66,7 @@ jobs:
           export PATH="/usr/lib/ccache:/usr/local/opt/ccache/libexec:$PATH"
           cmake --version
 
-          python3 setup.py install
+          python3 -m pip install .
           python3 -m pip install websockets
 
       - name: Start server for transducer models