Velero: Add bash completion support

[concaf]

It would be cool to have bash completion for ark.

Adding something similar to what kubectl does would be awesome i.e. ark completion bash/zsh

[ncdc]

Hi @containscafeine, that's a really good idea. Would you have any bandwidth to work on adding this functionality?

[concaf]

Yes, sir!

[arafatmohammed]

@containscafeine How do I add ark autocompletion to zsh?