Export install command, too

[blaggacao]

Since carapace has context awareness for a lot of shells, it is a good place to improve dx for users to implement install which would typically append a shell-specific string to a shell-specific rc-file.

[rsteube]

For registering the completion? Not too sure about this, so far been wary of messing with peoples init files.
Should be possible but things to consider here:

• Directly sourcing the completion is considered bad practice as it slows down shell startup time considerably.
  Been working on lazycomplete to circumvent this issue.

• Location of init files might vary (e.g. my .zshrc is now in ~/.config/zsh).

• Could slightly interfere with existing plugin managers or users way the config is written.

• Checking if config already exists could be a challenge. E.g. zsh needs additional config like compinit for which a call might already exist in a separate sourced file.

• Nushell is a bit of a special case as well

Not against it, but i haven't figured out which way i want to go with this yet.

The direction i've been going for so far is a supporting a user spec.
But that only make sense when carapace-bin is used.

For this a yaml file is simply placed in a specific folder, which works cross-shell and is loaded lazily.
It also enables embedding the completion in other commands like sudo example <TAB> or gum spin example <TAB>.

name: example
description: example completion
completion:
  positionalany: ["$_bridge.Carapace(example)"]