Add github actions support

Author: shana

.github/workflows/build.yml

@@ -0,0 +1,30 @@
+name: Build, Test, Pack
+
+on: [push]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v1
+    - name: Setup .NET Core
+      uses: actions/setup-dotnet@v1
+      with:
+        dotnet-version: 2.2.301
+    - name: Setup Node.js
+      uses: actions/setup-node@v1.1.0
+    - name: Build
+      env:
+        DOTNET_SKIP_FIRST_TIME_EXPERIENCE: 1
+        DOTNET_CLI_TELEMETRY_OPTOUT: 1
+      run: ./build.sh -r
+    - name: Test
+      env:
+        DOTNET_SKIP_FIRST_TIME_EXPERIENCE: 1
+        DOTNET_CLI_TELEMETRY_OPTOUT: 1
+      run: ./test.sh -r
+    - name: Pack
+      env:
+        DOTNET_SKIP_FIRST_TIME_EXPERIENCE: 1
+        DOTNET_CLI_TELEMETRY_OPTOUT: 1
+      run: ./pack.sh -r