fix(config): move --install-tab-completion to its own command

[amalthundiyil]

Description

The problem with the earlier approach is that the --install-tab-completion which should be an option is also trying to play the role of a command (also see koordinates/kart#648 (review)). This PR adds a new command instead of adding it as an option in a subcommand.

kart install tab-completion # to auto-detect shell and install tab completion

Related links:

• config: tab completion setup issues #701
• Tab Completion for Kart #643

Checklist:

• Have you reviewed your own change?
• Have you included test(s)?
• Have you updated the changelog?

[rcoup]

I feel like we might end up with other setup commands which are only useful once.

(I think it was my suggestion to move it under config, sorry)

Thoughts @craigds @olsen232 ?

[olsen232]

Hard to argue with the premise - it is a command, not an option, so if we make any distinction, that's where it should go.

It could be a subcommand if we don't want it at the top-level - if this is too much prominence for a one-off command - or if we expect to have more one-off commands like this.

It could maybe be kart config install-tab-completion (not sure if we can subcommand kart config, or if it has to be a special "group" command) or it could be kart install tab-completion

I think probably - perhaps more importantly than exactly what we call our commands - we need to one day customise the kart --help text so that it can give prominence to some commands ahead of others, maybe add some headings eg "common commands", "advanced", "setup commands"

[craigds]

LGTM