Add script to download aarch64 files

[c1728p9]

Description

This PR adds a script to download and verify the ISO files for aarch64 testing.

How Has This Been Tested?

This PR was tested by installing openqa on an aarch64 machine (Ampere Altra):

sudo ./install-openqa.sh
# Login to create default API key before running next command
sudo ./install-openqa-post-rocky.sh
sudo ./install-openqa-post-rocky-aarch64.sh
# Verify images show up correctly in openqa UI

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules