feat(authenticator): Allow retry if fetchAuthSession fails

[mattcreaser]

• PR conforms to Pull Request guidelines.

Issue #, if available:
#203

Description of changes:
If the initial fetchAuthSession fails during Authenticator startup, the resulting error will allow retry. See screenshot below.

How did you test these changes?
Produced failure and verified behaviour.

Documentation update required?

• No
• Yes (Please include a PR link for the documentation update)

General Checklist

• Added Unit Tests
• Added Integration Tests
• Security oriented best practices and standards are followed (e.g. using input sanitization, principle of least privilege, etc)
• Ensure commit message has the appropriate scope (e.g fix(liveness): message, fix(authenticator): message, fix(all): message)

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[mattcreaser]

We need retry for getCurrentUser failure as well.