Add action outputs?

I am looking for a way to get the FQDN of the deployed application.

I used to use the [`azure/webapps-deploy`](https://github.com/Azure/webapps-deploy) action which had an output called `webapp-url` which I could then use to populate the GitHub environments e.g.:
```yaml
deploy:
runs-on: ubuntu-latest

needs: build

environment:
name: "production"
url: ${{ steps.deploy-to-webapp.outputs.webapp-url }}

steps:
- name: Lowercase the repo name
run: echo "REPO=${GITHUB_REPOSITORY,,}" >>${GITHUB_ENV}

- name: Deploy to Azure Web App
id: deploy-to-webapp
uses: azure/webapps-deploy@v2
with:
app-name: ${{ env.AZURE_WEBAPP_NAME }}
publish-profile: ${{ secrets.AZURE_WEBAPP_PUBLISH_PROFILE }}
images: "ghcr.io/${{ github.repository }}:latest"
```