This adds support for allowing AWS ECR logins via multiple regions.
Functionality is quite similar to the existing support for multi-AWS
accounts. This adds in a new valid environment variable `AWS_REGIONS`
that can additionally be used to run the login against multiple regions.
Main changes are in `aws.ts` where `getRegion` is replaced by
`getRegions` which will construct and return a list rather than a
string. Since `getRegistriesData` already returns `regDatas` in a list
due to its support for multi-aws-accounts, all I really needed to add
was a `for-loop` wrapper to iterate on regions around the existing loop
that iterates on account IDs.
Signed-off-by: Helen Lim <hlim2@atlassian.com>
