Test GHA -> S3 for MSI builds

.github/workflows/msi_push.yaml

@@ -0,0 +1,23 @@
+name: Push MSI to S3
+on:
+    pull_request: {}
+env:
+  BUCKET_NAME : "element-desktop-msi.onprem.element.io"
+  AWS_REGION : "eu-central-1"
+permissions:
+  id-token: write
+  contents: read
+jobs:
+  S3PackageUpload:
+    runs-on: ubuntu-latest
+    steps:
+      - name: configure aws credentials
+        uses: aws-actions/configure-aws-credentials@v3
+        with:
+          role-to-assume: arn:aws:iam::264135176173:role/Push-ElementDesktop-MSI
+          role-session-name: githubaction-run-${{ github.run_id }}
+          aws-region: ${{ env.AWS_REGION }}
+      - name: Copy file to S3
+        run: |
+          echo ${{ github.run_id }} > test
+          aws s3 cp ./test s3://${{ env.BUCKET_NAME }}/