Sets up Emit for Auth Entry

This CL focuses on setting up the emit for the authentication entry
metrics, by identifying where in the API flow this may occur.
Further CLs will add more details.

Bug: 271135048
Test: Build + Won't Submit before E2E Test
Change-Id: I82c2f7477f585b0c43a6cf06e7a1f4982cbf5907
3 files changed