fix: Add error reporting to PRs with invalid workflows (#7930)

Hello all, I am finally taking the time to follow-up on #6277 to get this implemented :)

## Checklist

### Tests

- I added test coverage for Go changes...
  - [ ] in their respective `*_test.go` for unit tests.
  - [x] in the `tests/integration` directory if it involves interactions with a live Forgejo server.

### Documentation

- [ ] I created a pull request [to the documentation](https://codeberg.org/forgejo/docs) to explain to Forgejo users how to use this change.
- [x] I did not document these changes and I do not expect someone else to do it.

### Release notes

- [ ] I do not want this change to show in the release notes.
- [x] I want the title to show in the release notes with a link to this pull request.
- [ ] I want the content of the `release-notes/<pull request number>.md` to be be used for the release notes instead of the title.

<!--start release-notes-assistant-->

## Release notes
<!--URL:https://codeberg.org/forgejo/forgejo-->
- Bug fixes
  - [PR](https://codeberg.org/forgejo/forgejo/pulls/7930): <!--number 7930 --><!--line 0 --><!--description QWRkIGVycm9yIHJlcG9ydGluZyB0byBQUnMgd2l0aCBpbnZhbGlkIHdvcmtmbG93cw==-->Add error reporting to PRs with invalid workflows<!--description-->
<!--end release-notes-assistant-->

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/7930
Reviewed-by: Earl Warren <earl-warren@noreply.codeberg.org>
Co-authored-by: Antonin Delpeuch <antonin@delpeuch.eu>
Co-committed-by: Antonin Delpeuch <antonin@delpeuch.eu>

modules/actions/workflows.go

@@ -122,6 +122,14 @@ func DetectWorkflows(
 		events, err := GetEventsFromContent(content)
 		if err != nil {
 			log.Warn("ignore invalid workflow %q: %v", entry.Name(), err)
+			dwf := &DetectedWorkflow{
+				EntryName: entry.Name(),
+				TriggerEvent: &jobparser.Event{
+					Name: triggedEvent.Event(),
+				},
+				Content: content,
+			}
+			workflows = append(workflows, dwf)
 			continue
 		}
 		for _, evt := range events {