Generate fish completions

[coszio]

A bit of UX improvement,

• installs bfb fish completions in ~/.config/fish/completions
• adds "suggestions" feature to clap to get nice suggestions on typos

[timvisee]

I don't think it's right for regular builds to simply dump files across your host. Ideally the build process should not touch any files outside of the projects directory to keep it isolated.

I'd prefer to create a separate script instead, which you can invoke to install the latest shell completions.

Wdyt?

[coszio]

I think completions are nice to have than not have. There are plenty of other installations that create completions files without explicitly requesting them. From the POV of a user, less extra work when installing is a better experience.

I can think of another two solutions:

1. Use a separate script, or bfb argument to install completions (what you mentioned)
2. (can we set an uninstaller script?) Make sure to clean up completions on uninstall.
3. Log a line saying that completions have been installed somewhere.