actions: add test for reusable workflows (#839)

It is working although undocumented. It appears that Forgejo Actions users depend on it and breaking it would meet some non negligible push back. This test ensures that future Forgejo runner versions do not break what is working. This came to light because some fixes are necessary to the schema validation to allow for that to keep working (see https://code.forgejo.org/forgejo/act/pulls/194).

Reviewed-on: https://code.forgejo.org/forgejo/end-to-end/pulls/839
Reviewed-by: Michael Kriese <michael.kriese@gmx.de>
Co-authored-by: Earl Warren <contact@earl-warren.org>
Co-committed-by: Earl Warren <contact@earl-warren.org>

actions/example-workflow-call/.forgejo/workflows/reusable.yml

@@ -0,0 +1,27 @@
+on:
+  workflow_call:
+    inputs:
+      parameter1:
+        required: true
+        type: string
+
+jobs:
+  callee:
+    runs-on: docker
+    container:
+      image: code.forgejo.org/oci/node:22-bookworm
+      volumes:
+        - /srv/example:/srv/example
+    steps:
+
+      - run: |
+          set -x
+          test "${{ inputs.parameter1 }}" = "value1"
+
+      - name: save event
+        run: |
+          d=/srv/example/push/contexts/$FORGEJO_EVENT_NAME
+          mkdir -p $d
+          cat > $d/github <<'EOF'
+          ${{ toJSON(github) }}
+          EOF

actions/example-workflow-call/.forgejo/workflows/test.yml

@@ -0,0 +1,11 @@
+on:
+  push:
+
+jobs:
+  caller:
+    runs-on: docker
+    container:
+      image: code.forgejo.org/oci/node:22-bookworm
+    uses: ./.forgejo/workflows/reusable.yml
+    with:
+      parameter1: value1