chore: add checkov scan script (#653)

Add checkov scan for this repo to scan for vuln in infra.

### Checklist

- CI 🟢 

- [x] Follow the [manual testing
process](https://github.com/sourcegraph/deploy-sourcegraph-helm/blob/main/TEST.md)
- [x] Update
[changelog](https://github.com/sourcegraph/deploy-sourcegraph-helm/blob/main/charts/sourcegraph/CHANGELOG.md)
- [x] Update [Kubernetes update
doc](https://docs.sourcegraph.com/admin/updates/kubernetes)

### Test plan

- CI github action should be actively executing on all pull request

<!--
As part of SOC2/GN-104 and SOC2/GN-105 requirements, all pull requests
are REQUIRED to
provide a "test plan". A test plan is a loose explanation of what you
have done or
implemented to test this, as outlined in our Testing principles and
guidelines:

https://docs.sourcegraph.com/dev/background-information/testing_principles
  Write your test plan here after the "Test plan" header.
-->

---------

Co-authored-by: shivasurya <[email protected]>

Author: Shiva Sankar

.github/workflows/checkov.yml

@@ -0,0 +1,37 @@
+name: Checkov Scan
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  checkov-scan:
+    runs-on: ubuntu-latest
+    
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Set up Python
+        uses: actions/setup-python@v4
+        with:
+          python-version: '3.9'
+
+      - name: Install Checkov
+        run: pip install checkov
+        
+      - name: Write skip checks config
+        run: |
+            echo "${{ vars.CHECKOV_SKIP_CHECKS }}" > .checkov.yaml
+
+      - name: Run Checkov scan
+        run: |
+          checkov -d ./charts --output cli --output sarif --output-file-path console,results.sarif
+        continue-on-error: true
+
+      - name: Upload SARIF file
+        uses: github/codeql-action/upload-sarif@v3
+        with:
+          sarif_file: results.sarif