Add color and grouping of options in the help text

[joshka]

Using cargo-hack is more difficult than it could be because the options are presented in a single color with very little differentiation between one option and the next. When you compare this with most cargo commands, the grouping and colors help make it easy to discover and understand the way the options interact with each other. You have a similar layout in the documentation on the git page, but it would be nice to have this information directly available from -h and --help instead of having to read a markdown doc.

I suggest adding color and headings which group the options.

The direct benefit of this is that it provides a much easier onboarding for new users learning about the various options than a readme, and it acts like it's part of the clap ecosystem rather than being something different.

These two options would be fairly simple to achieve if the project used clap, but cargo-hack instead uses lexopt for options generation as well as a manually coded help text. I'm curious whether using lexopt is a preference that you'd prefer not to change, or whether you're instead amenable to using clap instead to gain the benefits of the clap derive macros and help generation.

If it's the latter, then I'm willing to submit a PR to update this and make the usability better, but I wanted to validate whether the choice of lexopt was a blocker before doing so.

[taiki-e]

These two options would be fairly simple to achieve if the project used clap, but cargo-hack instead uses lexopt for options generation as well as a manually coded help text. I'm curious whether using lexopt is a preference that you'd prefer not to change, or whether you're instead amenable to using clap instead to gain the benefits of the clap derive macros and help generation.

clap was not good for my Cargo subcommands (cargo-hack,cargo-llvm-cov,etc.) as it was not good with the Cargo subcommand style of propagation to the underlying command, is complex, and the recommended API has changed several times in the short term. For example, see the issues and comments referenced in taiki-e/cargo-llvm-cov#250.

The situation may have changed by https://github.com/crate-ci/clap-cargo, but it may be easier to simply hierarchize the help text than to investigate it.