Use dynamic name for CF stack

[mikkeloscar]

Right now the CF stack has the static name: egress-static-nat. This has the downside that you can't run two clusters with different stacks in the same AWS account. We should instead generate a dynamic CF stack name (ideally based on the clusterID #31) such that each cluster can have and manage its own stack.

We will still need to be backwards compatible and support existing stacks with the name egress-static-nat because if we were to migrate these stacks then we would change the NAT IPs which is not desired for existing users.