SPA proxy development server launch options

### Is there an existing issue for this?

- [X] I have searched the existing issues

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

The SPA development proxy can launch the development server multiple times, if the server doesn't respond quickly enough. This can happen infrequently when certificates are being re-created after expiry.

The result is the first server is running and the process becomes orphaned.
A new process is created and is unable to start 'normally' as resources (e.g. ports) are in use by the first process.

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In addition, both processes appear in-front of the IDE, which takes focus away from the IDE during debugging.

### Describe the solution you'd like

There should be the means of configuring the SPA proxy back-end to either wait or kill and re-launch the process. I propose that this is configurable to ensure anyone using the current functionality is not impacted. In cases where the process can take longer than the timeout, a user/developer can configure their project to behave differently.

In addition, it would be useful to be able to - by configuration - launch the command window (where the server back-end is running) in a background/minimised window to reduce the impact on development.

### Additional context

See additional analysis here: https://github.com/laingsimon/courage_scores/issues/770

A potential change is submitted here to aid with discussion of this topic: https://github.com/dotnet/aspnetcore/compare/release/6.0...laingsimon:aspnetcore:feature/54289-spa-proxy-launch-options