feat(backend gallery): add meta packages (#5696)

* feat(backend gallery): add meta packages

So we can have meta packages such as "vllm" that automatically installs
the corresponding package depending on the GPU that is being currently
detected in the system.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* feat: use a metadata file

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

---------

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>