test: add Actions dynamic matrix end-to-end test (#1261)

Reviewed-on: https://code.forgejo.org/forgejo/end-to-end/pulls/1261
Reviewed-by: earl-warren <earl-warren@noreply.code.forgejo.org>
Co-authored-by: Mathieu Fenniak <mathieu@fenniak.net>
Co-committed-by: Mathieu Fenniak <mathieu@fenniak.net>

actions/example-matrix-dynamic/.forgejo/workflows/test.yml

@@ -0,0 +1,49 @@
+on: [push]
+jobs:
+  define-matrix:
+    runs-on: docker
+    outputs:
+      scalar-value: ${{ steps.define.outputs.scalar }}
+      array-value: ${{ steps.define.outputs.array }}
+      matrix-value: ${{ steps.define.outputs.matrix }}
+    steps:
+      - id: define
+        run: |
+          echo 'scalar=scalar value' >> "$FORGEJO_OUTPUT"
+          echo 'array=["value 1", "value 2"]' >> "$FORGEJO_OUTPUT"
+          echo 'matrix={"dimension-1": ["d1 v1", "d1 v2"], "dimension-2": ["d2 v1", "d2 v2"]}' >> "$GITHUB_OUTPUT"
+
+  scalar-job:
+    runs-on: docker
+    needs: define-matrix
+    strategy:
+      matrix:
+        scalar:
+          - "${{ needs.define-matrix.outputs.scalar-value }}"
+          - hard-coded value
+    steps:
+      - run: |
+          set -x
+          [ "${{ matrix.scalar }}" = "scalar value" ] || [ "${{ matrix.scalar }}" = "hard-coded value" ] || exit 1
+
+  array-job:
+    runs-on: docker
+    needs: define-matrix
+    strategy:
+      matrix:
+        array: ${{ fromJSON(needs.define-matrix.outputs.array-value) }}
+    steps:
+      - run: |
+          set -x
+          [ "${{ matrix.array }}" = "value 1" ] || [ "${{ matrix.array }}" = "value 2" ] || exit 1
+
+  matrix-job:
+    runs-on: docker
+    needs: define-matrix
+    strategy:
+      matrix: ${{ fromJSON(needs.define-matrix.outputs.matrix-value) }}
+    steps:
+      - run: |
+          set -x
+          [ "${{ matrix.dimension-1 }}" = "d1 v1" ] || [ "${{ matrix.dimension-1 }}" = "d1 v2" ] || exit 1
+          [ "${{ matrix.dimension-2 }}" = "d2 v1" ] || [ "${{ matrix.dimension-2 }}" = "d2 v2" ] || exit 1