ci: .github/workflows/deploy.yml preview job sets gh environment (#18)

Motivation
* #17
* make preview environments easier to find by having our github workflow
files use the `environment` affordance to record when it deploys
preview/staging environments to cloudflare pages. That way they will be
browsable/clickable in the GitHub UI at
https://github.com/web3-storage/console/deployments

note
* [x] wait for cloudflare to not be down to ensure the CI workflow will
then pass #20

.github/workflows/deploy.yml

@@ -14,6 +14,9 @@ jobs:
     needs:
       - test
     runs-on: ubuntu-latest
+    environment:
+      name: ${{ (github.ref_name == 'main') && 'staging' || format('preview-{0}', github.ref_name) }}
+      url: ${{ (github.ref_name == 'main') && 'https://staging.console.web3.storage/' || steps.cloudflare_url.outputs.stdout }}
     steps:
       - uses: actions/checkout@v3
       - uses: ./.github/actions/pnpm