feat: add CompletionWithDesc helper (#2231)

The code has also been refactored to use a type alias for completion and a completion helper

Using a type alias is a non-breaking change and it makes the code more readable and easier to understand.

Signed-off-by: ccoVeille <3875889+ccoVeille@users.noreply.github.com>
Co-authored-by: Marc Khouzam <marc.khouzam@gmail.com>