Added Missing AWS IAM Profiles and Policies

The AWS IAM profiles and policies required to run Kargo on AWS
are no longer hosted in the kubernetes main repo since kube-up got
deprecated. Hence we have to move the files into the kargo repository.

contrib/aws_iam/kubernetes-minion-role.json

@@ -0,0 +1,10 @@
+{
+  "Version": "2012-10-17",
+  "Statement": [
+    {
+      "Effect": "Allow",
+      "Principal": { "Service": "ec2.amazonaws.com"},
+      "Action": "sts:AssumeRole"
+    }
+  ]
+}