AssumeRole uses STS to assume the given `role`.

ContainsString checks if array contains string.

GetRegion attempts loading the AWS region from ~/.aws/config.

LoadFiles return filtered map of relative to 'root' file paths; for filtering it uses shell file name pattern matching.

ParseEnv accepts an `env` slice from the command-line and returns a map.

ProfileAndRegionFromConfig attempts to load the .profile setting from `environment`'s config.

ReadIgnoreFile reads .apexignore in `dir` when present and returns a list of patterns.

Sha256 returns a base64 encoded SHA256 hash of `b`.