Improve completion for bash

[williamthome]

This PR improves the completion for bash.

Currently the improvements are:

• Profiles completion: typing rebar3 as <tab> gives a list of the rebar,config profiles, same for rebar3 clean --project/-p <tab>

Any tips or comments about this are welcome.

Note: For now I will do this for bash. Maybe in the future for fish and zsh.

[williamthome]

Yep I think that works! Thanks for updating this, much appreciated!

Thanks, @ferd! I will do some changes to add more completions, for example to rebar3 unlock <packagename> command, where the <packagename> will be suggested. I will come back when having some news.

[williamthome]

I am closing this PR in favor of #2858. Excellent job, @MarkoMin!