Support passing configurable logger to ECRHelper

[hasheddan]

Currently the ECRHelper uses a global logger and emits error logs on events such as a failure to parse the server URL. An error here makes sense in the common case where a user is using the ECR Credentials Helper explicitly for a URL, such as in a Docker auth config file. However, if ECRHelper is being consumed in a chain of credentials (e.g. k8schain), this error simply means that we cannot retrieve ECR credentials for this specific image reference. Ideally, the logger used by ECRHelper could be configured such that an error logs like the one emitted in this case can be easily discarded without having to set the global logger output to discard.

I am happy to implement this change if maintainers are on board 👍🏻

[hasheddan]

I believe this was fixed by #312! Thanks @imjasonh!