Move NGINX Bot to GitHub App (#1618)

Problem: Some operations are not possible from a GitHub Actions.

Solution: Make it into a GitHub App. This will also allow us to have
many more functionalities in the future.

.github/nginx-bot.yml

@@ -0,0 +1,5 @@
+prAssigneeFromIssueNumber: 583
+warnMissingIssue: true
+missingIssueMessage: |
+  Please make sure to include the issue number in the PR description to automatically close the issue when the PR is merged.
+  See [Linking a pull request to an issue](https://docs.github.com/en/issues/tracking-your-work-with-issues/linking-a-pull-request-to-an-issue) and our [Pull Request Guidelines](../docs/developer/pull-request.md) for more information.

.yamllint.yaml

@@ -1,8 +1,7 @@
 ---
-
 yaml-files:
-  - '*.yaml'
-  - '*.yml'
+  - "*.yaml"
+  - "*.yml"
 
 ignore:
   - deploy/helm-chart/templates/
@@ -39,7 +38,7 @@ rules:
     allow-non-breakable-words: true
     allow-non-breakable-inline-mappings: true
     ignore: |
-      .github/workflows/
+      .github/
       deploy/manifests/nginx-gateway.yaml
       deploy/manifests/crds
       tests/longevity/manifests/cronjob.yaml