fix(task): subcommand parser skips global args

[Cre3per]

Fixes #15290

I decided to slice args in flags_from_vec(), rather than in task_parse(), to avoid passing task_parse() more data than is necessary. This makes it easier to see that task_parse() doesn't care about the "--quiet" in deno --quiet task echo.

Not happy with the way I'm slicing the subcommand's args from args. I couldn't find anything in clap to get the index of the subcommand name, or a function like index_of() for subcommands. Suggestions are welcome.

[CLAassistant]

All committers have signed the CLA.

[niedzielski]

Hi @Cre3per! I'm not a maintainer just someone interested in seeing this patch merged! I just noticed that it looks like you have to sign the CLA if you want this code to be reviewed. Thanks either way!

[Cre3per]

Thanks for the reminder @niedzielski !

I pushed commits with a wrong email address, which I later amended, and thought the CLA checker was just slow to pick up the changes. I now force-pushed onto my fork.

[Cre3per]

@kt3k Github actions failure looks like #15385. Could you try re-running without changes?

[dsherret]

This index being out of sync with the raw_args index seems a bit error prone. In the interest of merging this for the release tomorrow, I'm going to push a change that keeps these in sync.

[dsherret]

Ok, I couldn't figure it out in a reasonable time. I moved this current code to be localized and your fix seems to work in a bunch of scenarios I tried so let's land it. Thanks!

[dsherret]

LGTM. Thanks!