ci: update the pr template and add comment-on-pr workflow (#5500)

Signed-off-by: M. Fatih Cırıt <mfc@autoware.org>

Author: xmfcx

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,23 @@
+## Description
+
+## Related links
+
+**Parent Issue:**
+
+- Link
+
+<!-- ⬇️🟢
+**Private Links:**
+
+- [CompanyName internal link]()
+⬆️🟢 -->
+
+## How was this PR tested?
+
+## Notes for reviewers
+
+None.
+
+## Effects on system behavior
+
+None.

.github/PULL_REQUEST_TEMPLATE/small-change.md

@@ -0,0 +1,25 @@
+name: comment-on-pr
+on:
+  pull_request_target:
+
+jobs:
+  comment-on-pr:
+    runs-on: ubuntu-22.04
+    permissions:
+      pull-requests: write
+    steps:
+      - name: Check out repository
+        uses: actions/checkout@v4
+
+      - name: Initial PR comment
+        uses: marocchino/sticky-pull-request-comment@v2
+        with:
+          message: |
+            Thank you for contributing to the Autoware project!
+
+            🚧 If your pull request is in progress, [switch it to draft mode](https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/proposing-changes-to-your-work-with-pull-requests/changing-the-stage-of-a-pull-request#converting-a-pull-request-to-a-draft).
+
+            Please ensure:
+            - You've checked our [contribution guidelines](https://autowarefoundation.github.io/autoware-documentation/main/contributing/).
+            - Your PR follows our [pull request guidelines](https://autowarefoundation.github.io/autoware-documentation/main/contributing/pull-request-guidelines/).
+            - All required CI checks pass before [marking the PR ready for review](https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/proposing-changes-to-your-work-with-pull-requests/changing-the-stage-of-a-pull-request#marking-a-pull-request-as-ready-for-review).