GR13 | Validation 3| Guest User Type BGs are not explicitly evaluated

[amrinderssc]

Describe the bug
Guest User Type BGs are not explicitly evaluated and handled under the message "BG UPNs provided do not exist in the environment"

Please also look at if Guest User API calls are successful considering guest users have a weird format such as "Ammy.amazing_gmail.com#EXT#@amrinderharikaoutlook.onmicrosoft.com"

To Reproduce
Create a Guest User
Add it to the KV for BGA1 or BGA2
Look at the non-compliant messages in the playbook

[amrinderssc]

Please add the similar logic to all the break glass accounts check using this functionality