Run fuzzing tests with go test -fuzz

In addition to oss-fuzz's CIFuzz (see #7052), this commit adds a small
shell script that run all fuzzing tests with go test -fuzz.

While running for 30 seconds would be too short to acutally find issues,
we want to make sure that these fuzzing tests are not fundamentally
broken.

Signed-off-by: Kazuyoshi Kato <katokazu@amazon.com>

.github/workflows/fuzz.yml

@@ -0,0 +1,41 @@
+name: Fuzzing
+on: [pull_request]
+jobs:
+  # Run all fuzzing tests. Some of them use Go 1.18's testing.F.
+  # Others use https://github.com/AdaLogics/go-fuzz-headers.
+  ci_fuzz:
+    name: CI Fuzz
+    runs-on: ubuntu-latest
+    steps:
+    - name: Build Fuzzers
+      id: build
+      uses: google/oss-fuzz/infra/cifuzz/actions/build_fuzzers@master
+      with:
+        oss-fuzz-project-name: 'containerd'
+        dry-run: false
+        language: go
+    - name: Run Fuzzers
+      uses: google/oss-fuzz/infra/cifuzz/actions/run_fuzzers@master
+      with:
+        oss-fuzz-project-name: 'containerd'
+        fuzz-seconds: 300
+        dry-run: false
+        language: go
+    - name: Upload Crash
+      uses: actions/upload-artifact@v1
+      if: failure() && steps.build.outcome == 'success'
+      with:
+        name: artifacts
+        path: ./out/artifacts
+
+  # Make sure all fuzzing tests which use Go 1.18's testing.F are
+  # runnable with go test -fuzz.
+  go_test_fuzz:
+    name : go test -fuzz
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/setup-go@v2
+        with:
+          go-version: 1.18
+      - uses: actions/checkout@v2
+      - run: script/go-test-fuzz.sh