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/flutter-linux.yaml

@@ -32,6 +32,7 @@ concurrency:
 
 jobs:
   flutter_linux:
+    if: false
     name: linux
     runs-on: ${{ matrix.os }}
     container: ubuntu:18.04
@@ -49,7 +50,7 @@ jobs:
         shell: bash
         run: |
           apt-get update -y
-          apt-get install -y build-essential jq git cmake 
+          apt-get install -y build-essential jq git cmake
           apt-get install -y curl
 
       - name: Setup Flutter SDK