Add CI for building FTS

Signed-off-by: Felix Wang <wangfelix98@gmail.com>

.github/workflows/build_feature_transformation_server.yml

@@ -0,0 +1,28 @@
+name: build_feature_transformation_server
+
+on:
+  push:
+    branches:
+      - master
+
+jobs:
+  build-docker-image:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v1
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v1
+      - name: Login to DockerHub
+        uses: docker/login-action@v1
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+      - name: Build and push
+        run: |
+          docker build \
+            --file sdk/python/feast/infra/transformation_servers/Dockerfile \
+            --tag feastdev/feature-transformation-server:`git rev-parse HEAD` \
+            .
+          docker push feastdev/feature-transformation-server:`git rev-parse HEAD`