Include Swift samples in CI verification

Author: ktoso

.github/workflows/pull_request.yml

@@ -106,3 +106,6 @@ jobs:
         run: "make jextract-generate"
       - name: Test Swift
         run: "swift test"
+      - name: Build (Swift) Sample Apps
+        run: |
+          find Samples/ -name Package.swift -depth 2 -exec swift build --package-path $(dirname {}) \;;