Enforce unique CloudFormation stack names

[fnesveda]

NOTE: this could be a good first task for a new DevOps engineer.

To prevent issues with overriding CloudFormation stacks because of a naming conflict, we need to ensure that the CloudFormation stacks have unique names.

This would be hard to enforce directly across the whole GitHub organizations, but we can split it into two parts:

• make sure that the stack names are prefixed with the repo that is trying to deploy them
• make sure that the stack names are unique in the repository

We could even make sure that the stack names contain the environment that they're being deployed to, and that they're being deployed to the right environment according to the name.

So there would be stack names like:

• apify-core-org-s3-buckets
• apify-web-member-iam-roles

TBD: should the environments be called org and member, or org, prod and staging?

Unfortunately, CloudFormation doesn't let you rename existing stacks, so we'll have to have some option to opt-out of these names for legacy stacks. We should not allow new stacks to be created with the wrong names, though. Maybe, if the legacy stack name is in the wrong format and the repo and account can't be inferred automatically, we could even have a mapping of stack name -> repo & AWS account that would verify that the stacks are being deployed to the correct account.