[RFE] Support for AWS `block_device_mappings` in `rancher2_machine_config_v2`

[kgtw]

Is your feature request related to a problem? Please describe.

Trying to deploy a latency sensitive node pool for etcd utilizing AWS EC2 instance types which support Instance Store so that we can take advantage of the improved performance characteristics of a locally attached SSD instead of EBS which has overhead of network latency.

Describe the solution you'd like

For the rancher2_machine_config_v2 resource to support the similar functionality provided via aws_launch_template, specifically the ability to define multiple block_device_mappings configurations which we can then configure etcd to use those block devices instead of the root ebs volume provided with the instance.

block_device_mappings {
  device_name  = "/dev/sdf"
  virtual_name = "ephemeral0"
}
block_device_mappings {
  device_name  = "/dev/sdg"
  virtual_name = "ephemeral1"
}

Describe alternatives you've considered

Additional context