Fix/snap (#141)

* fix(snap): build snap using explicitly pulled dependency

* ci(snap): add snap workflow

* feat(CI): snap publication channel depending on tags

* fix(CI): push tagged snap to candidate instead of stable

* fix(snap): use MICROROSAGENT_SUPERBUILD

.github/workflows/snap.yaml

@@ -0,0 +1,60 @@
+name: snap
+on:
+  push:
+    tags:
+      - '*'
+    branches:
+      - foxy
+  pull_request:
+    branches:
+      - foxy
+  workflow_dispatch:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    outputs:
+      snap-file: ${{ steps.build-snap.outputs.snap }}
+    strategy:
+      matrix:
+        architecture:
+        - linux/amd64
+        - linux/arm64
+    steps:
+    - uses: actions/checkout@v2
+    - uses: snapcore/action-build@v1
+      id: build-snap
+      with:
+        snapcraft-args: '--enable-experimental-extensions'
+
+    # Make sure the snap is installable
+    - run: |
+        sudo snap install --dangerous ${{ steps.build-snap.outputs.snap }}
+
+    # @todo Do some testing with the snap
+    - run: |
+        micro-ros-agent udp4
+    - uses: actions/upload-artifact@v3
+      with:
+        name: micro-ros-agent-snap
+        path: ${{ steps.build-snap.outputs.snap }}
+
+  publish:
+    if: github.ref == 'refs/heads/foxy' || startsWith(github.ref, 'refs/tags/')
+    runs-on: ubuntu-latest
+    needs: build
+    strategy:
+      matrix:
+        architecture:
+        - linux/amd64
+        - linux/arm64
+    steps:
+    - uses: actions/download-artifact@v3
+      with:
+        name: micro-ros-agent-snap
+        path: .
+    - uses: snapcore/action-publish@v1
+      with:
+        store_login: ${{ secrets.STORE_LOGIN }}
+        snap: ${{needs.build.outputs.snap-file}}
+        release: ${{ startsWith(github.ref, 'refs/tags/') && 'candidate' || 'edge'}}