CLI commands suggestions

[sebastienros]

• aspire run on an already running apphost (started with detach) could probably restart it, or detect it's already running and display an error
• I think aspire run --detach should not display the update message
• aspire stop should exit with 0 if nothing is running, not 7 and an error message
• aspire add on a detached running app will fail because the apphost server can't be built as locked
• create aspire start to provide the same behavior as aspire run --detach