support buildkit cache export/import

- Add support for buildkit cache export/import
- Enable GHA cache for universe test (using buildkit v0.9 GHA support)

Signed-off-by: Andrea Luzzardi <aluzzardi@gmail.com>

.github/workflows/ci.yml

@@ -89,8 +89,15 @@ jobs:
           mkdir -p ~/.config/dagger
           echo "$DAGGER_AGE_KEY" > ~/.config/dagger/keys.txt
 
+      - name: Expose GitHub Runtime
+        uses: crazy-max/ghaction-github-runtime@v1
+
       - name: Integration test
+        env:
+          DAGGER_CACHE_TO: "type=gha,scope=integration"
+          DAGGER_CACHE_FROM: "type=gha,scope=integration"
         run: |
+          env
           make core-integration
 
   universe:
@@ -116,6 +123,12 @@ jobs:
           mkdir -p ~/.config/dagger
           echo "$DAGGER_AGE_KEY" > ~/.config/dagger/keys.txt
 
+      - name: Expose GitHub Runtime
+        uses: crazy-max/ghaction-github-runtime@v1
+
       - name: Universe Test
+        env:
+          DAGGER_CACHE_TO: "type=gha,scope=universe"
+          DAGGER_CACHE_FROM: "type=gha,scope=universe"
         run: |
           make universe-test