[Github Actions] Set pull request environment name

A new preview environment is created per pull request which create a new subdomain with the pull request number. My static web app is configured with custom authentication using Azure Active Directory. In the app registration, you must specify the redirect uri.
The redirect uri do not support wildcard at the subdomain level so we need to automate the creation of the redirecturi for that specific pull request in a pipeline. Currently you can set the production branch (production_branch) name and the deployment environment (deployment_environment) for feature branches but you cannot change the pull request environment name.

It would be a nice feature to add an attribute to be able to configure the pull request environment name.

```yaml
- name: Deploy
uses: Azure/static-web-apps-deploy@v1
with:
...
production_branch: "main"
deployment_environment: "dev"
pr_environment: "pr"
....
```