refactor: move getContainerActionPaths into step interface (#13)

* allows to specialize local vs remote action implementation
* allow paths like ./.. for local action

Closes https://gitea.com/actions-oss/act-cli/issues/12

Reviewed-on: https://gitea.com/actions-oss/act-cli/pulls/13
Co-authored-by: ChristopherHX <christopher.homberger@web.de>
Co-committed-by: ChristopherHX <christopher.homberger@web.de>

pkg/runner/testdata/uses-local-dot-dot-dir-symlink/push.yml

@@ -0,0 +1,19 @@
+on: push
+jobs:
+  test-symlinks:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Create symlink
+        run: |
+          mkdir action-dir
+          cat << 'EOF' > action-dir/action.yml
+          runs:
+            using: composite
+            steps:
+            - run: echo test
+              shell: bash
+          EOF
+          ln -s $PWD/action-dir ../action-sym
+      - run: cat ../action-sym/action.yml
+      - name: Verify symlink
+        uses: ./../action-sym