ci: add workflow for static binary.

The CI workflow will test that building the IOC is always working. The
resulting tarball for tags will also be published in the project's
release page.

.github/workflows/build.yml

@@ -0,0 +1,18 @@
+name: IOC build and release
+permissions:
+  contents: write
+on:
+  push:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Build
+        run: docker compose up
+      - name: Release
+        uses: softprops/action-gh-release@v2
+        if: startsWith(github.ref, 'refs/tags/')
+        with:
+          files: rffe-epics-ioc-*.tar.gz