Support for completion in other shells (fish, zsh, etc.)

[gaocegege]

cobra supports bash_completion, that's awesome. Is there a way to support other shells?

ref kubernetes/kubernetes#30763

[xh3b4sd]

Kind of duplicate of #107. Lets upvote there and get some movement.

[babysnakes]

Please see my note in #107. I'll appreciate any input on my trial at native zsh completion.

Thanks.

[boynux]

We are also interested in FiSH integration.

[github-actions]

This issue is being marked as stale due to a long period of inactivity

[z3ntu]

It looks like #1048 added support for fish shell and there's e.g. #1070 for zsh

[marckhouzam]

With Cobra now offering shell completion for bash, zsh, fish and powershell, I believe we can close this issue.

/cc @jharshman @jpmcb