Add sym file action

Based off of pokeemerald's workflow YML

.github/workflows/build.yml

@@ -50,6 +50,21 @@ jobs:
       - name: Modern
         run: |
           make -j${nproc} modern
+          
+      - name: Move symfiles
+        if: ${{ github.event_name == 'push' }}
+        run: |
+          cp -v *.sym symbols/
+          echo "SYMBOLS_COMMIT_MSG=$( git log --format=%s ${GITHUB_SHA} )" >> $GITHUB_ENV
+
+      - name: Update symfiles
+        if: ${{ github.event_name == 'push' }}
+        uses: EndBug/add-and-commit@v7
+        with:
+          branch: symbols
+          cwd: "./symbols"
+          add: "*.sym"
+          message: ${{ env.SYMBOLS_COMMIT_MSG }}
 
       # only run OK when pushed to master
       - name: Run OK webhook