workflows: Set up batch fuzzing every 24 hours

So instead of fuzzing each and every PR for 10minutes, we just fuzz
30mins every 24 hours, at 6am UTC which should be a time when US and
Europe might be least active.

.github/workflows/cflite_batch.yml

@@ -0,0 +1,34 @@
+name: ClusterFuzzLite batch fuzzing
+on:
+  schedule:
+    - cron: '0 6 * * *'  # UTC 6am every day.
+permissions: read-all
+jobs:
+  BatchFuzzing:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        sanitizer:
+        - address
+        - undefined
+        - memory
+    steps:
+    - name: Build Fuzzers (${{ matrix.sanitizer }})
+      id: build
+      uses: google/clusterfuzzlite/actions/build_fuzzers@v1
+      with:
+        sanitizer: ${{ matrix.sanitizer }}
+    - name: Run Fuzzers (${{ matrix.sanitizer }})
+      id: run
+      uses: google/clusterfuzzlite/actions/run_fuzzers@v1
+      with:
+        github-token: ${{ secrets.GITHUB_TOKEN }}
+        fuzz-seconds: 1800 # 30 mins
+        mode: 'batch'
+        sanitizer: ${{ matrix.sanitizer }}
+        # Optional but recommended: For storing certain artifacts from fuzzing.
+        # See later section on "Git repo for storage".
+        # storage-repo: https://${{ secrets.PERSONAL_ACCESS_TOKEN }}@github.com/OWNER/STORAGE-REPO-NAME.git
+        # storage-repo-branch: main   # Optional. Defaults to "main"
+        # storage-repo-branch-coverage: gh-pages  # Optional. Defaults to "gh-pages".