Add backport workflow

Taking a look at the [backport Action](https://github.com/grafana/grafana-github-actions/blob/main/backport/action.yml#L5).

> GitHub token with issue, comment, and label read/write permissions

It looks to be covered by the default permissions for [`GITHUB_TOKEN`](https://docs.github.com/en/actions/security-guides/automatic-token-authentication#permissions-for-the-github_token).

I'm guessing that the Action does require extra permissions since all other instances of the workflow are using PATs or apps but we can test this by merging this PR and trying a backport.

Signed-off-by: Jack Baldry <jack.baldry@grafana.com>

.github/workflows/backport.yml

@@ -0,0 +1,26 @@
+name: Backport PR creator
+on:
+  pull_request_target:
+    types:
+      - closed
+      - labeled
+
+jobs:
+  main:
+    if: github.repository == 'grafana/beyla'
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout Actions
+        uses: actions/checkout@v4
+        with:
+          repository: grafana/grafana-github-actions
+          path: ./actions
+          ref: main
+      - name: Install Actions
+        run: npm install --production --prefix ./actions
+      - name: Run backport
+        uses: ./actions/backport
+        with:
+          token: ${{ secret.GITHUB_TOKEN }}
+          labelsToAdd: backport
+          title: "[{{base}}] {{originalTitle}}"