Support sharing AMIs across multiple AWS accounts

[p5]

Value Statement

As a Cloud Engineer
I want to publish a single AMI and use it across the organization
So reduce the amount of duplication or manual work

Notes

Right now, if I wanted to deploy an AMI across many accounts, I would either need to rerun the BIB pipeline across each account, or go into the AWS Console and manually update the permissions on that AMI to make it accessible.

If we could provide BIB with a list of accounts that BIB uses to attach a policy to the AMI, this would simplify using Bootc and BIB in a multi account environment.

This could also be extended to support creating public AMIs (although the use-case for this is significantly less).

[tuananh]

I think pushing to s3 + create ami is a lot slower than copy AMI from 1 region to another