More control of application instances

**Is your feature request related to a problem? Please describe.**

Azure Spring Apps application instances cannot be controlled, for instance it is not possible to reboot or kill a specific application instance.
I had an application with some instances failing due to failing dependency. The application requires a connection to a Postgresql server and there were no more available connections when some application instances started. Once fixed the connections availability it was not possible to reboot the failed instances.
The application remains in update or failed stated and didn't allow to do a manual scale-in.
The only way to fix this situation was to completely stop the application, with a service disruption, and then start the application again.
Another impact is that seems that failed instances were charged to the bill, so there costs charged for failed instances that was not possible to stop.

**Describe the solution you'd like**
Provide a restart action for application instances. For instance in the CLI or Azure Portal, provide an action to restart an application.
Provide a delete action for application instances. That would automatically scale-in the application, reducing the amount of instances.
**Describe alternatives you've considered**

The only solution found was stopping the application, fix the issue, and start again. It implies a service disruption.

**Describe the Customer Impact**

As described above, the only way to fix it is by stopping the application with a service disruption.
Failed application instances are billed and there is no way to stop them without service disruption.

**Additional context**

Add any other context or screenshots about the feature request here.

**Can we contact you for additional details?** Y/N
Y
If yes, please send us your contact information to AzureSpringCloud-Talk@service.microsoft.com and include the issue number in the email title.

未指定任何仓库文件、测试或入口点。首先定位 Azure Spring Apps CLI 和 Portal 的实例管理界面，然后与维护者确认重启和删除行为的范围。完成的标准是：就实现目标和验收检查达成一致，以便在不停止应用程序的情况下控制一个实例。

由索引模型根据 Issue 内容生成。