RHEL_AWS: RHEL and Windows AMI names have changed

[benblasco]

The names of RHEL and Windows AMIs in AWS have changed, and so the templated for the group_vars/all_example.yml is now incorrect.

group_vars/all_example.yml needs to change as follows OLD:

< rhel_ver:                         "rhel8"
< win_ver:                          "win2016"

---

NEW:

> rhel_ver:                         "RHEL-8"
> win_ver:                          "Windows_Server-2016"