format-check: add collect errors job

The Github UI for required checks does not integrate with the workflows
described in the .github directory. Currently jobs that are never
started due to conditional execution are not even reported, so the UI
shows "expected" and locks up merges.

Collect format errors so that the Github UI can be happy to track one job that
is always executed. This job will fail if any of the format-check jobs
failed or were cancelled, and will be ignored (but reported) otherwise.

Signed-off-by: Luca Burelli <l.burelli@arduino.cc>

Author: pillo79

.github/workflows/format_check.yml

@@ -58,3 +58,13 @@ jobs:
           clang-format-version: '19'
           check-path: ${{ matrix.path['check'] }}
           exclude-regex: ${{ matrix.path['exclude'] }}
+
+  verify-format:
+    name: Collect job errors
+    runs-on: ubuntu-latest
+    if: cancelled() || contains(needs.*.result, 'failure')
+    needs:
+      - format-check
+    steps: 
+      - name: Notify failure
+        run: exit 1