ASPIRE_EXTRA_ARGS env var

### 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 use aspire in automations and CI, and I am repeating the same flags over and over again for all invocations:
`--apphost $APPHOST_DIR`
`--isolated`
`--non-interactive`
etc.

Being able to set an env var once in the CI and then just calling the different commands can simplify the CI script and reduce errors.

### Describe the solution you'd like

Read extra args from an environment variable or equivalent solution enabling setting the flags once during the run of a script.

### Additional context

_No response_

The issue names no files, tests, or command entry points; begin by tracing how Aspire CLI commands parse repeated flags and where shared options are defined. Define the environment-variable behavior across invocations, then verify that the affected automation and CI command paths consistently accept the configured arguments.

Written by the indexing model from the issue text.