chore(java_templates): add lint/static analysis presubmit checks for samples (#727)

* chore(java_templates): add lint/static analysis presubmit checks for samples

* chore: fix trailing whitespace

Author: chingor13

synthtool/gcp/templates/java_library/.github/workflows/samples.yaml

@@ -0,0 +1,24 @@
+on:
+  pull_request:
+name: samples
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-java@v1
+        with:
+          java-version: 8
+      - name: Run checkstyle
+        run: mvn -P lint --quiet --batch-mode checkstyle:check
+        working-directory: samples/snippets
+  static:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-java@v1
+        with:
+          java-version: 8
+      - name: Run PMD & Spotbugs
+        run: mvn -P lint --quiet --batch-mode compile pmd:cpd-check spotbugs:check
+        working-directory: samples/snippets