Added support for g3s.xlarge and g4dn.xlarge instances

[acap4z]

Added support for g3s.xlarge and g4dn.xlarge instances by changing base AMI to "Deep Learning Base AMI (Amazon Linux 2)". This one has Nvidia drivers and CUDA support so it seems to meet the requirements to be used in NPK. It has the advantage of supporting a wider range of instance types, including the newest G4 and P4. G4 has been benchmarked and shows the best results in terms of performance/$.

Changing to this AMI may solve some other limitations such as the one explained in #50 related to regions.

[c6fc]

Interesting idea. I'll test this in dev when I get a chance. There are many more places where new instances types have to be configured in order for them to function correctly, but I think it's a valid thing to add.