* [auth-swift] User dummy keychain storage container for unit tests
* [auth-swift] Finish refactor to inject a fake keychain instance for macOS tests
* Fix CI
* Review
* Resolve TODO, restricting method's visibility
* Further restrict API visibility and remove unnecessary test
- There exists a private keychain method that was only used in two places
(another keychain API and in a keychain unit test). The unit test was testing
the private method in a way that it will never be used. And, because
of the test reference, the visibility was internal instead of private.
Given all of this, it seems reasonable to lock down the APIs
visibility to private and remove the unneeded unit test.
* Commit new TODO
* Commit new TODO (pt. 2)
Paul Beusterien