Create a way to get a structured representation of a given .NET CLI command

[baronfel]

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

It can be useful for tools that are doing feature-probing of the .NET CLI to provide some structured representation of the CLI Command being invoked.

Describe the solution you'd like

This structured representation should provide access to

• the names and aliases of the command (if any)
• the options on the command
• the arguments on the command
• the subcommands on this command (recursively)

In this output, hidden items should be shown.

Additional context

The least grammar impacting way to do this would be a Directive, a la dotnet run [structure format=json], but there's space for some kind of global flag that could be used as well (dotnet run --dump-grammar?).

This was first requested in dotnet/aspire#7112 (comment).
NuGet experiences in DevKit also drive themselves based on the CLI capabilities and could make use of this.

[MiYanni]

@baronfel Is this a dup of this? Which was a dup of this?

[baronfel]

Hah! Yes it is, but mine is the best one :D

[KalleOlaviNiemitalo]

In #41142 + #46717, dotnet test reads an environment variable or a configuration file and then decides whether to use a TestingPlatformCommand for Microsoft.Testing.Platform or DocumentedCommand for VSTest. Those do not support all the same options, so the "structured representation" would depend on which test runner the project uses. That is not a problem if the caller uses the output for command completion immediately, but becomes a problem if the caller translates the output to a command completion script and saves that for later use.