feat: bash completion

[ankush]

Complete following things:

• site names
• command/options

[gavindsouza]

Adding some reference of past efforts - I had a half-baked zsh script that I used for site completions (https://github.com/gavindsouza/bench-autocomplete), the idea then was to built a template script that (re)generates the autocompletion file which was a lot faster than dealing with https://github.com/frappe/bench/blob/develop/completion.sh

[hupq22]

It sounds like you're referencing your previous efforts with the zsh script for site completions found in your bench-autocomplete repository. The goal was to create a template script that could regenerate the autocompletion file more efficiently compared to the existing completion.sh from the Frappe Bench repository.

This approach could indeed streamline the process and improve performance by reducing the complexity involved in managing autocompletions. If you have specific ideas or updates you'd like to incorporate into this script, sharing them could foster further enhancements in the community.

Let me know if you need any help with this!