Rewrote AWS Terraform for Kargo

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

contrib/terraform/aws/modules/vpc/variables.tf

@@ -0,0 +1,24 @@
+variable "aws_vpc_cidr_block" {
+    description = "CIDR Blocks for AWS VPC"
+}
+
+
+variable "aws_cluster_name" {
+    description = "Name of Cluster"
+}
+
+
+variable "aws_avail_zones" {
+    description = "AWS Availability Zones Used"
+    type = "list"
+}
+
+variable "aws_cidr_subnets_private" {
+  description = "CIDR Blocks for private subnets in Availability zones"
+  type    = "list"
+}
+
+variable "aws_cidr_subnets_public" {
+  description = "CIDR Blocks for public subnets in Availability zones"
+  type    = "list"
+}