Adding a CI action to validate helm chart renderings (#199)

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## What was changed
- WISOTT
- I have added some very basic "helm lint and helm template" validation
checks in this PR. One could very well build on this by adding something
like "is the image that is being pulled a valid docker image". I decided
to keep it small and just get this in, for now, so that we have a
pipeline to test things against.

## Why?
- to detect failures quite early

## Checklist
<!--- add/delete as needed --->

1. Closes <!-- add issue number here -->
#191 

3. How was this tested:
<!--- Please describe how you tested your changes/how we can test them
-->

4. Any docs updates needed?
<!--- update README if applicable
      or point out where to update docs.temporal.io -->

Author: Shivs11

.github/workflows/helm-validate.yml

@@ -0,0 +1,61 @@
+name: Helm Chart Validation
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+
+permissions:
+  contents: read
+
+jobs:
+  helm-lint:
+    name: Lint Helm Chart
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Helm
+        uses: azure/setup-helm@v3
+
+      - name: Lint chart
+        run: helm lint --strict helm/temporal-worker-controller
+
+  helm-template:
+    name: Template Helm Chart
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Helm
+        uses: azure/setup-helm@v3
+
+      - name: Template with default values
+        run: helm template test-release helm/temporal-worker-controller
+
+      - name: Template with namespace creation
+        run: |
+          helm template test-release helm/temporal-worker-controller \
+            --set namespace.create=true
+
+      - name: Template with auth proxy disabled
+        run: |
+          helm template test-release helm/temporal-worker-controller \
+            --set authProxy.enabled=false \
+            --set metrics.disableAuth=true
+
+  helm-validate-succeed:
+    name: All Helm Validations Succeed
+    needs:
+      - helm-lint
+      - helm-template
+    runs-on: ubuntu-latest
+    if: always()
+    env:
+      RESULTS: ${{ toJSON(needs.*.result) }}
+    steps:
+      - name: Check results
+        run: |
+          if [[ -n $(echo "$RESULTS" | jq '.[] | select (. != "success")') ]]; then
+            exit 1
+          fi