[Build] [Unity] delta-unity project GitHub action test workflow (delta-io#4857)

## 🥞 Stacked PR
Use this [link](https://github.com/delta-io/delta/pull/4857/files) to
review incremental changes.
-
[**stack/unity_github_workflow_tests**](delta-io#4857)
[[Files changed](https://github.com/delta-io/delta/pull/4857/files)]

---------
#### Which Delta project/connector is this regarding?
<!--
Please add the component selected below to the beginning of the pull
request title
For example: [Spark] Title of my pull request
-->

- [ ] Spark
- [ ] Standalone
- [ ] Flink
- [ ] Kernel
- [X] Other (Unity)

## Description

`delta-unity` project GitHub action test workflow

## How was this patch tested?

CI Run

## Does this PR introduce _any_ user-facing changes?

No.

Author: scottsand-db

.github/workflows/unity_test.yaml

@@ -0,0 +1,30 @@
+name: "Delta Unity"
+on: [push, pull_request]
+jobs:
+  test:
+    name: "Delta Unity Tests"
+    runs-on: ubuntu-24.04
+    env:
+      SCALA_VERSION: 2.12.18
+    steps:
+      - uses: actions/checkout@v3
+      - uses: technote-space/get-diff-action@v4
+        id: git-diff
+        with:
+          PATTERNS: |
+            build.sbt
+            version.sbt
+            unity/**
+            kernel/**
+            storage/**
+            .github/workflows/unity_test.yaml
+      - name: install java
+        uses: actions/setup-java@v3
+        with:
+          distribution: "zulu"
+          java-version: "8"
+        if: steps.git-diff.outputs.diff
+      - name: Run Unity tests with coverage
+        run: |
+          ./build/sbt "++ ${{ env.SCALA_VERSION }}" clean coverage unity/test coverageAggregate coverageOff -v
+        if: steps.git-diff.outputs.diff