cli: move jj co alias to config file, so it can be overridden

[martinvonz]

This way users can override jj co to mean jj new if they want to get rid of the warning.

Checklist

If applicable:

• I have updated CHANGELOG.md
• I have updated the documentation (README.md, docs/, demos/)
• I have updated the config schema (cli/src/config-schema.json)
• I have added tests to cover my changes

[yuja]

Thanks!

[martinvonz]

@thoughtpolice, @PhilipMetzger: are you okay with this?

[thoughtpolice]

Yeah, LGTM. I should have done this in the original PR, honestly, since I wanted to free up these names as early as possible so people could reuse co. Thanks!

[PhilipMetzger]

LG. I think for the future, we should just provide the aliases as built-in config, instead of defining them via clap. Then everyone is free to define them as is.

[martinvonz]

I think for the future, we should just provide the aliases as built-in config, instead of defining them via clap.

I hesitate to do that for two reasons:

• Aliases configured in clap could show up in the help text, though it seems that clap doesn't currently do that (it does for flag aliases)
• By having a builtin alias like jj undo, we can refer to that in hints and such. Maybe it's still fine to do that and just tell people who define aliases.undo = ["new"] to not shoot themselves in the foot

[PhilipMetzger]

I don't mind having a set of core aliases built-in but convenience aliases should be defined in the config.