feat(auth): Support signInWithProvider for non-default instances

[rohitsangwan01]

Description

This PR fixes the use of signInWithProvider for Firebase Auth instances that are not the default instance in Android

Previously, attempting to use signInWithProvider with a non-default instance would result in unexpected behaviour. This change ensures that the correct Firebase Auth instance is used when calling signInWithProvider, regardless of whether it is the default instance or not.

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