Adding secrets to the site

1. In infra/appService.bicep, add the name and value of the private key

2. In infra/appService-create-pr-slot.bicep, do the same thing

3. In .github/workflows/template-build.yml, add the key in

• keyVault – Secrets

• Docker – Build and push

4. In DockerFile, add the key as ARG and ENV properties