[FR] please add onSignIn to auth function trigger

[Thaina]

[REQUIRED] Version info

9.15.0

node:
16.18.1

firebase-functions:
0.9.0

firebase-tools:
11.18.0

firebase-admin:
11.2.0

[REQUIRED] Expected behavior

Have function to trigger after user signin like onCreate function

functions.auth.user().onSignIn((user,context) => {
});

Because beforeSignIn is blocking function and trigger just before user successfully signed in. It not a proper function to take a log and monitoring user signing in or taking any complicate action. I want this function to just notify the server and can run the long running task

[inlined]

Barring new infrastructure in the auth team's backend, have you considered kicking off a task queue function during beforeSignIn so you can run the long-running task asynchronously?

[Thaina]

That was an option I have considered but still it add more complication and dependency to the system just for very simple use case