feat: bash rewrite

[cristiand391]

ref: #319

rewrite of the bash completion to fix:

1. script only completing 1st flag of a command
2. complete known flag values

this was just for fun while playing with claude code in ~1hr, could have been done in 30min with the right context loop.

cristiand391@pop-os:~/code/gh/oclif-org/plugin-autocomplete$ sf org login web --alias cd --
--browser              --client-id            --instance-url         --scopes               --set-default-dev-hub
--client-app           --flags-dir            --json                 --set-default          --username

cristiand391@pop-os:~/code/gh/oclif-org/plugin-autocomplete$ sf org login web --browser
chrome   edge     firefox

[skip-validate-pr]