`aspire deploy` command is now feature flagged

[captainsafia]

A bit of a late change for 9.4 but the aspire deploy command is now behind a feature flag.

See dotnet/aspire#10613.

To enable the command, the user must run:

$ aspire config set features.deployCommandEnabled true

After that, the deploy subcommand will be available in the CLI.

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Associated WorkItem - 474407