Update github actions for Delta Kernel

Based off of #1785.

Updates our current `test.yaml` to not run when there are only changes in `kernel/`.

Adds a separate action for future `kernel/` tests. Currently this just compiles the code.

### Testing

I merged these changes to my own fork and created these PRs to check

allisonport-db#11 Changes to `core/src/main/scala/org/apache/spark/sql/delta/Snapshot.scala`
- https://github.com/allisonport-db/delta/actions/runs/5125555163/jobs/9218878662?pr=11
- https://github.com/allisonport-db/delta/actions/runs/5125555163/jobs/9218878794?pr=11

allisonport-db#12 Changes to `build.sbt`
- https://github.com/allisonport-db/delta/actions/runs/5125557362/jobs/9218883935?pr=12
- https://github.com/allisonport-db/delta/actions/runs/5125557362/jobs/9218884043?pr=12

allisonport-db#13 Changes to `examples/scala/src/main/scala/example/ChangeDataFeed.scala`
- https://github.com/allisonport-db/delta/actions/runs/5125558258/jobs/9218886849?pr=13
- https://github.com/allisonport-db/delta/actions/runs/5125558258/jobs/9218886959?pr=13

allisonport-db#14 Changes to `run-tests.py`
- https://github.com/allisonport-db/delta/actions/runs/5125560869/jobs/9218892247?pr=14
- https://github.com/allisonport-db/delta/actions/runs/5125560869/jobs/9218892419?pr=14

allisonport-db#15 Changes to `kernel/build.sbt` (Spark tests SHOULD NOT run)
- https://github.com/allisonport-db/delta/actions/runs/5125973036/jobs/9219853307?pr=15 (skipped)
- https://github.com/allisonport-db/delta/actions/runs/5125973036/jobs/9219853403?pr=15 (skipped)

Closes #1786

Signed-off-by: Allison Portis <[email protected]>
GitOrigin-RevId: cd5449a905c057f61f66afd7dfd5e5cb19348270

.github/workflows/kernel_test.yaml

@@ -0,0 +1,16 @@
+name: "Delta Kernel Tests"
+on: [push, pull_request]
+jobs:
+  test:
+    runs-on: ubuntu-20.04
+    env:
+      SCALA_VERSION: 2.12.15
+    steps:
+      - uses: actions/checkout@v3
+      - name: install java
+        uses: actions/setup-java@v3
+        with:
+          distribution: "zulu"
+          java-version: "8"
+      - name: Compile code  # TODO: run tests later on
+        run: cd kernel && build/sbt compile

.github/workflows/test.yaml

@@ -1,4 +1,4 @@
-name: "Delta Lake Tests"
+name: "Delta Spark Tests"
 on: [push, pull_request]
 jobs:
   test:
@@ -10,6 +10,12 @@ jobs:
       SCALA_VERSION: ${{ matrix.scala }}
     steps:
       - uses: actions/checkout@v3
+      - uses: technote-space/get-diff-action@v4
+        id: git-diff
+        with:
+          PATTERNS: |
+            **
+            !kernel/**
       - name: install java
         uses: actions/setup-java@v3
         with:
@@ -49,7 +55,9 @@ jobs:
           pipenv run pip install twine==4.0.1
           pipenv run pip install wheel==0.33.4
           pipenv run pip install setuptools==41.0.1
+        if: steps.git-diff.outputs.diff
       - name: Run Scala/Java and Python tests
         run: |
           pipenv run python run-tests.py --coverage
           cd examples/scala && build/sbt "++ $SCALA_VERSION compile"
+        if: steps.git-diff.outputs.diff