Delegate action implementation to gradle/actions/setup-gradle

From v3 onwards, the `gradle-build-action` will be soft deprecated in preference
of `gradle/actions/setup-gradle`, which is a drop-in replacement. Version numbers
for these 2 actions will remain in sync.

Workflows that use `gradle/gradle-build-action` will transparently delegate to
`gradle/actions/setup-gradle`. At a later date, a deprecation warning will be added
to `gradle/gradle-build-action`, encouraging users to migrate.

All of the repository sources have been migrated to the `gradle/actions` repository,
and `gradle/actions/setup-gradle` has been released with `v3.0.0-beta.6`.
Going forward, releases will be first performed for `gradle/actions/setup-gradle`,
with a parallel release of `gradle/gradle-build-action` soon afterward.

Releasing as `gradle/gradle-build-action@v3` will allow dependabot to encourage users
to upgrade from `v2`. The deprecation warning (to be added later) will encourage users
to migrate to `gradle/actions/setup-gradle`.

action.yml

@@ -136,15 +136,44 @@ inputs:
 outputs:
   build-scan-url:
     description: Link to the Build Scan® generated by a Gradle build. Note that this output applies to a Step executing Gradle, not to the `gradle-build-action` Step itself.
+    value: ${{ steps.setup-gradle.outputs.build-scan-url }}
   dependency-graph-file:
     description: Path to the GitHub Dependency Graph snapshot file generated by a Gradle build. Note that this output applies to a Step executing Gradle, not to the `gradle-build-action` Step itself.
+    value: ${{ steps.setup-gradle.outputs.dependency-graph-file }}
   gradle-version:
     description: Version of Gradle that was setup by the action
+    value: ${{ steps.setup-gradle.outputs.gradle-version }}
 
 runs:
-  using: 'node20'
-  main: 'dist/main/index.js'
-  post: 'dist/post/index.js'
+  using: "composite"
+  steps:
+    - name: Setup Gradle
+      id: setup-gradle
+      uses: gradle/actions/setup-gradle@v3.0.0-beta.6
+      with:
+        gradle-version: ${{ inputs.gradle-version }}
+        cache-disabled: ${{ inputs.cache-disabled }}
+        cache-read-only: ${{ inputs.cache-read-only }}
+        cache-write-only: ${{ inputs.cache-write-only }}
+        cache-overwrite-existing: ${{ inputs.cache-overwrite-existing }}
+        cache-encryption-key: ${{ inputs.cache-encryption-key }}
+        gradle-home-cache-includes: ${{ inputs.gradle-home-cache-includes }}
+        gradle-home-cache-excludes: ${{ inputs.gradle-home-cache-excludes }}
+        gradle-home-cache-cleanup: ${{ inputs.gradle-home-cache-cleanup }}
+        add-job-summary: ${{ inputs.add-job-summary }}
+        add-job-summary-as-pr-comment: ${{ inputs.add-job-summary-as-pr-comment }}
+        dependency-graph: ${{ inputs.dependency-graph }}
+        dependency-graph-continue-on-failure: ${{ inputs.dependency-graph-continue-on-failure }}
+        artifact-retention-days: ${{ inputs.artifact-retention-days }}
+        build-scan-publish: ${{ inputs.build-scan-publish }}
+        build-scan-terms-of-service-url: ${{ inputs.build-scan-terms-of-service-url }}
+        build-scan-terms-of-service-agree: ${{ inputs.build-scan-terms-of-service-agree }}
+        arguments: ${{ inputs.arguments }}
+        build-root-directory: ${{ inputs.build-root-directory }}
+        generate-job-summary: ${{ inputs.generate-job-summary }}
+        gradle-home-cache-strict-match: ${{ inputs.gradle-home-cache-strict-match }}
+        workflow-job-context: ${{ inputs.workflow-job-context }}
+        github-token: ${{ inputs.github-token }}
 
 branding:
   icon: 'box'