Created a GitHub Action to generate the Third Party report. (#2033)

Signed-off-by: David Venable <dlv@amazon.com>

.github/workflows/third-party-generate.yml

@@ -0,0 +1,54 @@
+# This workflow generates the THIRD-PARTY file and creates a PR from the changes.
+# For more information see: https://github.com/marketplace/actions/create-pull-request
+
+name: Third Party Generate
+
+on:
+  workflow_dispatch:
+
+jobs:
+  generate:
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Set up JDK 11
+      uses: actions/setup-java@v1
+      with:
+        java-version: 11
+    - name: Checkout Data-Prepper
+      uses: actions/checkout@v2
+
+    - name: Generate Third Party Report
+      run: ./gradlew --no-daemon generateThirdPartyReport
+
+    - name: Get Git metadata
+      run: |
+        echo GIT_SHORT_HASH=`git rev-parse --short "$GITHUB_SHA"` >> $GITHUB_ENV
+        echo GITHUB_REF_NAME=${GITHUB_REF#refs/heads/} >> $GITHUB_ENV
+
+    - name: GitHub App token
+      id: github_app_token
+      uses: tibdex/github-app-token@v1.5.0
+      with:
+        app_id: ${{ secrets.APP_ID }}
+        private_key: ${{ secrets.APP_PRIVATE_KEY }}
+
+    - name: Create Pull Request
+      uses: peter-evans/create-pull-request@v4
+      with:
+        token: ${{ steps.github_app_token.outputs.token }}
+        add-paths: THIRD-PARTY
+        commit-message: 'Generated THIRD-PARTY file for ${{ env.GIT_SHORT_HASH }}'
+        signoff: true
+        branch: third-party/third-party-${{ env.GIT_SHORT_HASH }}-to-${{ env.GITHUB_REF_NAME }}
+        delete-branch: true
+        title: 'Generated THIRD-PARTY file for ${{ env.GIT_SHORT_HASH }}'
+        body: |
+          Generated `THIRD-PARTY` file with:
+
+          ```
+          ./gradlew --no-daemon generateThirdPartyReport
+          ```
+
+          Branch: ${{ env.GITHUB_REF_NAME }}
+          Commit: ${{ env.GIT_SHORT_HASH }}