`aspire run` should try to find the best suitable AppHost in the solution

[Kralizek]

Is there an existing issue for this?

• I have searched the existing issues

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

When executing aspire run you need to provide the path to the AppHost. It would be a nice QoL improvement if the CLI could find the AppHost project and target it automatically.

This would work under the assumption that:

• the user is in the directory of the solution file
• there is only one solution file in the current directory
• the AppHost project is part of the solution

Describe the solution you'd like

On start, the CLI should

• check if the path to the AppHost project was explicitly specified as an argument. If so, use that
• if not, find a solution file in the current directory. If no solution file or more than one solution file is found, return error and terminate. Otherwise, select solution.
• cycle through all the projects in the solution and find the AppHost project. If no AppHost project or more than one is found, return error and terminate. Otherwise select project.
• start the AppHost

Optionally, it could save the information somewhere in AppData for future executions.

Additional context

No response

[davidfowl]

@mitchdenny made changes here #8892.

There are more improvements to come but this accomplishes the goal.