CI: Add check that verifies the results of other checks

To properly use merge queues, it is necessary to mark certain checks as
"required" in the branch protection rules. However, this doesn't scale
with matrix jobs and would require manual tweaks of the CI jobs change.
The new analyze job simplifies this by allowing the branch protection
rule just check for that job. All further dependencies are then
configured within the CI config.

.github/workflows/tests.yml

@@ -269,6 +269,21 @@ jobs:
           go mod tidy
           git diff --exit-code go.mod go.sum
 
+  analyze:
+    name: Analyze results
+    needs: [test, cross_compile, lint]
+    if: always()
+
+    permissions: # no need to access code
+      contents: none
+
+    runs-on: ubuntu-latest
+    steps:
+      - name: Decide whether the needed jobs succeeded or failed
+        uses: re-actors/alls-green@05ac9388f0aebcb5727afa17fcccfecd6f8ec5fe
+        with:
+          jobs: ${{ toJSON(needs) }}
+
   docker:
     name: docker
     runs-on: ubuntu-latest