Cannot have completion for multiple functions

[fearphage]

If you have two tools built on yargs, they will clobber each other. Based on the current implmenetation, they will both define a function (_yargs_completions()) and one will overwrite the other. The last one will win. I'm addressing this now in related issue (#831). I just wanted to log it so it is known.

[bcoe]

@jacobator @gardenappl as folks using yargs' completion functionality, any thoughts on this long standing bug? I wonder what a good approach would be

[jacobator]

@bcoe https://github.com/yargs/yargs/blob/master/lib/completion-templates.ts. It looks like for zsh there's an app-specific function defined _{{app_name}}_yargs_completions() while it's generic _yargs_completions() for bash. Should be an easy fix. I can test and create a PR this evening.