[feat][plugin-cli] support parsing unconfigured argmuents

[J-ZhengLi]

In clap, there are two options for positional args which I found quite useful, they are allow_hyphen_values and trailing_var_arg. Which make it easy to parse arguments that are not per-configured.

Why

Let's say I'm writing a GUI wrapper to another program that has many CLI options, and I want the user to start my program with the same options of that other program (i.e. cargo).

So if the user run my-program build --vcs none --lib --edition 2024 -v hello_world, I want the parser to collect all arguments after build without me redefine all those same options.

In clap, I can use something like this:

enum Subcommands {
    Build {
        #[arg(
            trailing_var_arg = true,
            allow_hyphen_values = true,
            value_name = "ARGS"
        )]
        extra_args: Vec<String>,
    }
}

But I don't know if its possible to do the same thing using the cli plugin