Add Azure Spring Apps Standard tier

Add Spring Apps Standard tier:
- Add bicep template in `core/host` to deploy `AI Shopping Cart Service` to Azure Spring Apps standard tier
- Name of the bicep template: `spring-apps-standard.bicep`
- Add a parameter in `main.bicep` to select Spring Apps plan.
- Parameter name: `springAppsPlan`
- Parameter allowed values: `Consumption`, `Standard`, `Enterprise`
- Default value: `Consumption`
- When the value of `springAppsPlan` is Standard, the Azure Container Apps environment should not be deployed and the front-end should be deploy to Azure Static Web Apps.
- A new YAML file standard should be available to deploy the front-end to static web app. This YAML file should be rename to azure.yaml if the standard plan needs to be use
- A new `README_standard.md` should be available at the root of the repository
- In the root `README.md`/Application Architecture, a link to the standard tier readme should be added.
- The setup of the options (environment variable) to choose the plan needs to be described at the end of the quickstart guide and point also to `README_standard.md`
- A new Azure DevOps pipeline and a new GitHub workflow should be created for the standard plan

> Please provide us with the following information:
> ---------------------------------------------------------------

### This issue is for a: (mark with an `x`)
```
- [ ] bug report -> please search issues before submitting
- [x] feature request
- [ ] documentation issue or request
- [ ] regression (a behavior that used to work and stopped in a new release)
```

### Minimal steps to reproduce
> N/A

### Any log messages given by the failure
> N?A

### Expected/desired behavior
> Sample application can be deployed to Azure Spring Apps standard

### Versions
> 1.0.0

### Mention any other details that might be useful

> ---------------------------------------------------------------
> Thanks! We'll be in touch soon.

core/host と main.bicep 配下にある既存のデプロイファイルを確認し、現在の README とデプロイ自動化を比較してください。Issue で説明されている Standard プランのテンプレート、選択パラメーター、Static Web Apps の構成、ドキュメント、Azure DevOps パイプライン、GitHub ワークフローを追加してください。サンプルが Container Apps をデプロイせずに Azure Spring Apps Standard にデプロイされ、セットアップが文書化されていれば完了です。

索引モデルが issue の本文から書いたものです。