[WIP] Add RHEL8 template for v2v testing

[nachandr]

Purpose or Intent

PRT Run

[dajoRH]

I detected some fixture changes in commit b7a7f64

The global fixture rhel81_template was changed, but I didn't find where it's used.
The global fixture rhel81_template_modscope was changed, but I didn't find where it's used.
Please, consider creating a PRT run to make sure your fixture changes do not break existing usage 😃