support concurrent access to API credentials

[synfinatic]

TL;DR: users using the AWS_PROFILE integration may require concurrent access to credentials which the keyring API and underlying data stores don't really support.

So first fix is to do basic locking in some kind of OS agnostic way.

Additionally should consider placing each IAM role into it's own object so that each role is independent.

Long term: use the ECS server for caching?