Add config file support for break glass accounts

[adhilto]

💡 Summary

Allow users to indicate which accounts are break glass accounts

Motivation and context

For common controls, we assert that there should be between 2 and 8 super admin accounts but note that exceptions are allowed for break class accounts. Unless we allow the users a way to specify the names of the break glass accounts, ScubaGoggles is actually unable to make this exception.

Implementation notes

Related epic: #161

Acceptance criteria

• Break glass accounts can be specified in the config file
• Feature has been documented in the Readme files