samples: add presubmit lint check (#131)

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Synth log will be available here:
https://source.cloud.google.com/results/invocations/a79f8a17-dbb5-42d4-99e9-73d2b5ffda4d/targets

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Source-Link: googleapis/synthtool@9602086
Source-Link: googleapis/synthtool@c3caf07

.github/workflows/samples.yaml

@@ -0,0 +1,14 @@
+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

synth.metadata

@@ -4,7 +4,7 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-bigqueryreservation.git",
-        "sha": "a79329163884966a80211d255382587020e89966"
+        "sha": "2203863e152d8cafba10a47c9c0718fa8f744d66"
       }
     },
     {
@@ -19,7 +19,7 @@
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "f8823dec98277a9516f2fb6fae9f58b3a59a23e1"
+        "sha": "9602086c6c5b05db77950c7f7495a2a3868f3537"
       }
     }
   ],
@@ -43,6 +43,7 @@
     ".github/release-please.yml",
     ".github/trusted-contribution.yml",
     ".github/workflows/ci.yaml",
+    ".github/workflows/samples.yaml",
     ".kokoro/build.bat",
     ".kokoro/build.sh",
     ".kokoro/coerce_logs.sh",