[Aspire CLI] Enable running commands against a PID

### 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.

I am trying to run many commands one after another and not waste time on each cli command searching for running apphosts. I would rather capture the PID of the aspire start command and pass the PID from there to all future commands.

### Describe the solution you'd like

PID = $(aspire start)

aspire wait api --apphost $PID
aspire describe api --apphost $PID
...

Without each command searching for a running apphost.

### Additional context

Could work really well with the proposal of ASPIRE_EXTRA_ARGS where an env var containers a list of default parameters to all cli commands: https://github.com/microsoft/aspire/issues/16826

Start with the Aspire CLI entry points for start, wait, and describe, focusing on how --apphost is currently resolved. Use the proposed PID workflow and the linked ASPIRE_EXTRA_ARGS issue as context; done means subsequent commands can accept the PID from aspire start without searching for a running apphost.

Written by the indexing model from the issue text.