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/macos-jni.yaml

@@ -52,8 +52,8 @@ jobs:
           cmake \
             -D BUILD_SHARED_LIBS=ON \
             -D CMAKE_BUILD_TYPE=Release \
-            -DCMAKE_OSX_ARCHITECTURES=$arch \
-            -DSHERPA_ONNX_ENABLE_JNI=ON \
+            -D CMAKE_OSX_ARCHITECTURES=$arch \
+            -D SHERPA_ONNX_ENABLE_JNI=ON \
             -DCMAKE_INSTALL_PREFIX=./install \
             ..