Add various GitHub environment variables (#604)

* define GITHUB_ACTION_PATH #603

* Add more environment variables

* Add job name

Note: the job name gets a suffix for matrix builds, but this is not part of the env var

* fix: remove unnecessary variables

* feat: add `RepositoryOwner`

credit: @KnisterPeter

* feat: add test for `getGithubContext()`

Co-authored-by: Ryan (hackercat) <me@hackerc.at>

pkg/runner/testdata/uses-composite/composite_action/action.yml

@@ -41,6 +41,15 @@ runs:
         fi
       shell: bash
 
+    - run: |
+        if [ -z "$GITHUB_ACTION_PATH" ]; then
+          exit 1
+        fi
+        if [ -z "${{ github.action_path }}" ]; then
+          exit 2
+        fi
+      shell: bash
+
     # Let's send up an output to test
     - run: echo "::set-output name=test_output::test_output_value"
       shell: bash