[FEATURE] CLI autocomplete for inline --project + --config

[Grraahaam]

Describe the solution you'd like

CLI autocompletion for --projects and --configs, useful when maintaining and working with multiple projects in a single workspace. Here's some examples :

# project : inline
> doppler secrets --project <TAB>
project-one
project-two
project-three

# project : inline / config : inline
> doppler secrets --project project-two --config <TAB>
dev
stg
prd

# project : .doppler.yaml
> doppler secrets --project project-two --config <TAB>
dev
stg
prd

Describe alternatives you've considered

Using doppler setup everytime, but it's quite inconvenient. Meanwhile, the same function may be used I guess since it shows exactly what's expected ✌🏽

[Piccirello]

Closed by #379