quickstart script for Linux, Mac, Windows

[mudler]

Is your feature request related to a problem? Please describe.
Many users face issues deploying LocalAI in their local environment. Even if LocalAI's first target is servers, and to run as a backend service, would be good to offer a simple bash script that helps people getting started - for instance by selecting the correct image by detecting if the user has a GPU, or installing the required components (docker, docker-nvidia, etc).

Describe the solution you'd like
A quickstart.sh that can be linked from the documentation and served as a static asset from the repository. The docs are already served by this repository, so that should be quite an easy task

Describe alternatives you've considered
Keep things as is, but I think this is quite important as we have #1373

Additional context