CLI tool: recursive derives and attributes

[tadeohepperle]

Fixes #1353

This PR introduces an optional appendix of comma separated values to the CLI arguments derive-for-type and attributes-for-type. Right now, the appendix arguments are only checked for containing "recursive", but we could add more options in the future.

I verified that these commands work with and without the recursive flag:

subxt codegen --derive-for-type xcm::v2::multilocation::MultiLocation=Clone,recursive
subxt codegen --attributes-for-type "xcm::v2::multilocation::MultiLocation=#[foofoo],recursive"

[jsdw]

Looks good to me, but it's branched off #1290 I think so hard to tell if I'm missing anything right now.

Probably best to avoid doing too much on top of large PRs until they merge, because it becomes a pain all of a sudden if said PRs have comments that need addressing, though in this case it's fairly small :)

[tadeohepperle]

Looks good to me, but it's branched off #1290 I think so hard to tell if I'm missing anything right now.

Yeah, I did not know you guys would be so fast with the review, #1290 was so close to being merged, so I based it on it to avoid merge conflicts later :)

[jsdw]

Looks great!

str_equals_str_comma_maybe_recursive_parser is a strange name, but I don't have any great suggestions for it!

[lexnv]

We could probably have a few unit-tests for this. Would str1=str2,a,b,c,recursive also be a valid syntax?

I'd also probably rename this to type_parser or something similar

[lexnv]

Nice one! 👍

Would be good to have a few test scenarios for str_equals_str_comma_maybe_recursive_parser to make sure we only capture the intended form, overall looks good!

[lexnv]

Should we reject this format? 🤔

Maybe we could also check that we expect this function to panic on these inputs since they are invalid

[tadeohepperle]

Good point, let's reject it. To keep the possibility open to add other attributes (similar to recursive) in the future I implemented a simple match over the trailing attributes:

let mut recursive = false;
for r in split_rest {
    match r {
        "recursive" => {
            recursive = true;
        }
        _ => return None,
    }
}