[Feature Request] Allow optional control over vertical and horizontal display

[a2ush]

Request

The current implementation defaults to horizontal, so only horizontal views are generated. https://github.com/awslabs/diagram-as-code/blob/601056c873298e2f2312b3f3ffbe8be6b458d77c/internal/types/group.go#L55

It's better to be able to switch the display with an option.

Example

$ awsdac <input CloudFormation template> --cfn-template --vertical