Add TF_VAR_ to terraform env

* Dynamically retrieve aws_bastion_ami latest reference by querying AWS rather than hard coded

* Dynamically retrieve the list of availability_zones instead of needing to have them hard coded

* Limit availability zones to first 2, using slice extrapolation function

* Replace the need for hardcoded variable "aws_cluster_ami" by the data provided by Terraform

* Move ami choosing to vars, so people don't need to edit create infrastructure if they want another vendor image (as suggested by @atoms)

* Make name of the data block agnostic of distribution, given there are more than one distribution supported

* Add documentation about other distros being supported and what to change in which location to make these changes

* Add comment line and documentation for bastion host usage

* Take out unneeded sudo parm

* Remove blank lines

* revert changes

* take out disabling of strict host checking

* Point apiserver address to 0.0.0.0
Added loadbalancer api server address
* Update documentation

Rewrote AWS Terraform deployment for AWS Kargo. It supports now
multiple Availability Zones, AWS Loadbalancer for Kubernetes API,
Bastion Host, ...

For more information see README