Make EBS type configurable in mount points for ec2 providers

RIght now we have 3 fields when configuring mount points:
Device Name, Virtual Name, and Size

If Virtual Name is set and Size is empty, it would try to request an instance store and when Virtual Name is empty and Size is set - EBS volume.

There are multiple EBS volume types like gp2, iops, etc but the default one is standard and that's what we currently use. We want to be able to switch to gp2 now and have an option to pick iops type in the future (it will also require to provide the number of iops).